Leaky Cobra and broken fan mount

Coolant leak

I have had a coolant leak for some time from the thermostat housing. Unfortunately there is no drain point in the system, so a hose needs to be disconnected. Messy!

First I drained down the system and removed the thermostat housing. This was cleaned up where it mated to the block. Next I applied Hylomar blue sealant to the mating surfaces. After a bit of fiddling I got the thermostat and housing back in place, bolted up and filled ......... but it still leaked. So I repeated the process. It leaked again! So a glass of wine was called for.

After relaxing a bit, I thought of three reasons why this may be happening - the thermostat was not being correctly aligned, the bolts were too long and not allowing the housing to be nipped up or both.

So the next day I checked the bolts and sure enough one was not going in to the block far enough. The bolt was shortened a little to allow it to screw in fully.

Next I fit the rubber thermostat gasket in to the housing, using sealant in the recess where the rubber gasket sits. Then I put two tie wraps through the top of the thermostat and threaded these through the housing. I located the thermostat in place, making sure that the pressure release thingy was in the correct place (there is a recess in the rubber seal). Next I fixed the tie wraps around a bolt to secure the thermostat in the right place and so that it could not be moved whilst fixing. Sealant was applied yet again to the clean mating surface, before the housing was offered up and bolted in place. The tie wraps were removed, the hose reconnected and the jubilee clip tightened. The system was then re-filled gradually, making sure that no air was trapped (tip - get the front of the car higher than the back). Success!

Thermostat housing re-fitted

Radiator fan

Whilst messing about stopping the leak above, I noticed that two of the fan fixings on the driver's side had broken after only 1,200 miles!

Broken fan fixing. Tie wrap can now be seen below it.

What I should have done was to fit tie wraps as well to help stop the mountings moving. I have ordered new fan fixings to replace the broken ones. Guess that is the problem of such a big fan.

Just topped 1000 miles!

The Cobra is now ready for its first oil change after 1000 miles. I needed to do this before the Northern Cobra Club North York Moors Run at the weekend.

Almost 5 litres of  Mobil 1 and a new K&N filter from CarPartsForLess were used. The new filter, an HP 1007, has a 'nut' fitted to aid removal, however it is a little longer, but when fitted it is still above the lower extremity of the exhaust so should be ok.

The front of the car needed jacking up to get at the oil drain plug and the filter. A plastic carrier bag helped to catch the filter and the oil from the filter and an oil drain can caught the old oil.

The new filter rubber ring was coated with engine oil and the filter was partly filled before it was fitted to help with the process. After pouring the new oil in to the engine, it was allowed to settle before checking the level with the dipstick. When it looked to be at the correct level, the engine was run for a few minutes to circulate the oil, before finally topping up.

Job done!

ECU map

Dave from Canems came today and adjusted the engine map and flashed a new version of the ECU software.

Dave revising the map

Whilst at it, Dave set the soft cut and hard cut rev limiters (6300 rpm and 6500 rpm respectively). The immobiliser was also set up. The fobs are used to unset the immobiliser, the tacho doing a sweep to confirm that it has been unset.

The engine now starts quicker and runs much better. Thanks Dave!

First engine start!

I had taken my time getting here I was told.

On the big day I had two helpers/observers in Keith Akerman (built a GD 427) and Steve Hughes (building a GD 427). Steve was the camera and sound man. Keith the eyes on the engine bay etc. I must admit that I was nervous and excited. Anyone who says they are not nervous is fibbing!

Before I turned the Chevy LS6 engine over, we checked the Schrader valve on the fuel rail. It still leaked. Not the start to the day I had wanted. After a quick trip to Halfords we returned with a valve tool and a new valve (I will change this for a genuine part as soon as it arrives from the States). Changing the valve was a quick job and it worked, no more fuel leaks!

Next we checked the dip stick to make sure that the oil level was were it should be. When I turned over the engine a few days ago without the plugs in I had over 30 lbs of oil pressure, so that was ok. We checked the coolant and all connections. The cap from the coolant header tank was left loose at first in case there was any trapped air. I had plenty of trapped air too!

The car was pushed out of the garage on to the drive to avoid any fumes or blackening my new cabinets. Car chocked in place, fire extinguisher ready and bonnet up .......... Ignition switched on. There was the sound from the fuel pump and an ignition light. Good start. Now just press the start button. Go on then, do it!

8 seconds or so turning over and she fired and ran. Grin from ear to ear! Thanks Kyle (engine builder). Here is a video of the big start up taken and edited by Steve. Look out for the child in me! TIP: Use a PC to view this video as it needs a Flash player.

At first there was some smoke and some steam - no worries as I had spilt some brake fluid and coolant earlier so could explain this. Whilst it was running we checked that all header pipes were going a nice bronze colour to indicate that there was a spark/heat coming from all 8 cylinders. No leaks!

Next we checked that the fan was coming on and sucking in to the radiator, rather than blowing forward. Of course it was going the wrong way. Then we checked the gauges (fuel, volts, oil pressure, oil temp and water temp) - all okay there. Oil pressure up at 60 lb or more. Alternator belting out power. Fan cut in at around 80 deg. Still no leaks!

After turning off the engine, I swapped the wires to the fan around to suck, rather than blow. We also noted that the fuse to the fan had just blown, as the rating was too low at 20 amps - Keith saw the fan twitch just as the fuse blew. This was changed to a 30 amp fuse.

We then started it up again and again (yes we all tried it). In amongst the activity, Keith squeezed the coolant pipes to move any trapped air. There was heat in the heater flow and return pipes. All looked okay and it sounded good too. Neighbours came out to see what all the noise was. The Mrs thought it was a plane, but it went on too long. Great feeling!

So another milestone completed in my GD build. Again thanks to Keith and Steve for all their help and encouragement.

Preparation for engine switch on

Oil and plugs

I drained some oil as recommended by the engine builder. So jack up the car again to get access.

Oil drain plug to right of centre

It is now at the top of the range shown on the dipstick.

The plugs were really difficult to get back in as there is very little room, so not looking forward to servicing the engine!

ECU

This was connected using the big multi-plug on the loom. It fits with one end in the slot first, before pushing the multi-plug flat against the ECU. Finally it is locked in place with the handle on the multi-plug.

ECU connector on loom

Now all sorts of things work, including the fuel pump.

Fuel

I turned on the ignition and heard the fuel pump run. Next I purged the near side fuel rail via the valve at the front.

Valve at end of fuel rail

This did not re-seal itself as expected. This may be some swarf from the fuel pipe. Apparently I should have purged from the fuel pipe, not the fuel rail.  So note this mistake. The fuel pipe flexible hose needs to be disconnected before fuel is pumped to the engine. Catch the fuel in a container and dispose of it.

Next I noticed another leak from one of the fuel hoses at the rear from the fuel pump. So I jacked up the back of the car this time to gain access. It was easy to see which hose it was and to tighten the union.

Dashboard

Whilst attempting to fit the dash and the column shroud, I removed the ignition barrel again, but couldn't get it back in and the ignition switch connections were tight against the shroud. When squeezed the ignition turned on!

Dashboard in but column shroud not right

So with the fuel rail and the ignition switch issues, sadly I have abandoned the plan to start the engine tomorrow.

Better day today

Electrical

Had Paul Brown look at the wiring today. He sorted out the remaining electrical issues. Most issues seemed to be bad earths.

So the following are now sorted:

• Indicators
• Headlight flasher
• All gauge back lights
• Courtesy lights (they had no live supply)
• Starter motor

All appears to be working well now, including the other items. Relief!

Oil

So it turns over now and there does appear to be a little too much oil in the engine. Will let it settle overnight, then dip it again. If it is still too full, I will let a drop out, then check for adequate oil pressure.

Sorry, no photos today.

Tomorrow's jobs

I need to check the oil level, connect the ECU and re-fit the plugs. Tidy up the wiring with tie wraps, then fit the dash, under trays and steering wheel. Once that is done, I think it is ready to fire up, with a bit of luck!

Not a good day in the garage today

Coolant

No visible signs of leaks. Good news.

Engine

No visible oil leaks either. So I removed the plugs ready to turn the engine over and get oil pressure. The 8 plugs are really difficult to get at and were not easy to remove.

And it went downhill from here.

Tried to turn over the engine - switched on the ignition and hit the starter button. Nothing! I then connected the fuel pump wire to the battery in case there was any electrical connection here. Still nothing. Will sleep on that.

Fuel

Put some unleaded in the tank and no leaks. Good start. But no fuel pump sound. Urghhhh.

Brakes

Jacked up the car. Connected the Eezibleed system to the reservoir and a  tyre (gets pressure from here which allows you to do it on your own). The new cap leaked - easy enough to solve, I thought. So I rescued the old one from the bin! Bin diving is not a lot of fun. Fitted the old cap and great no leaks from the reservoir, but ........

Bled the rear brakes whilst keeping an eye on the brake fluid container and the reservoir. Then I noticed a great big puddle of brake fluid at the front! It was coming from a master cylinder where it joined the brake pipe. At first it was just dripping in to the off-side compartment, but then it started running out through some holes and on to the garage floor, which is when I noticed it.

Cleaned up. Packed up. Fed up!

Preparing for start up

Preparing the engine

The engine has not been run since it was collected - almost 18 months ago. So before I attempt to start it, it needed some lubrication.

I had spoken to Andy at GD and to the engine builder. As the engine had run on the dyno it wasn't a first start, so oil would still be present in the pump. The advice from the engine builder was to remove the rocker covers, then add a litre of oil to each side. The oil was poured over the rockers/lifters, springs and down the pushrod bores. The latter required a "pump action" oil can to squirt the oil in to the pushrod bores, which are above the rocker assembly. Once this was done the rocker covers etc were re-fixed to each side and the engine left overnight so that the oil drained down and lubricated the top end of the engine.

Tomorrow, after checking for leaks, I will add the rest of the oil to the engine. Then I will remove the plugs, disconnect the ECU and turn it over until I have oil pressure. Lots of max 20 second bursts is best for the starter I have been told.

Wipers

Today I bent the wiper arms to line up the blades with the lower edge of the screen. I bent them in a vice with jaw protectors. The bending was trial and error until they lined up right. Once they were positioned correctly, I extended the arms so that the sweep was 380 mm. This is done by sliding the arms out a little away from the pivot point. When I was happy that the length was okay, I locked the arms in place by moving the little locking plate (near to the pivot point) to be parallel to the main arm.

Wipers lined up with bottom of windscreen

Seat belt anchorages

There was a locating hole in one corner of each anchorage. A small hole was drilled in the centre of each anchorage locating hole and a self tapping screw inserted to stop the captive bolt moving. I made sure that the eye bolt was mounted with the hole pointing towards the sides of the car, so that the eye was in line with the seat belt tension.

Seat belt anchorage located by self tapper

Hopefully this will satisfy Mr IVA.

A couple of outstanding points have been sent the Andy, but no response as yet.

How the Chevy LS engine is made

Here is a link to a video that shows how the LS engine is built. http://www.powernationtv.com/post/how-the-ls7-and-lt4-are-made

ABCDE of Cobra building!

Accelerator

I have a fly by wire accelerator pedal, so the loom has provision for this. I drilled the holes for the fitting plate and a hole big enough to allow the connector to pass through. This was attached with M5 button head bolts and nyloc nuts. The plate was made by Keith Akerman, fabulous piece of engineering, as expected from him.

Accelerator pedal with connection made. Note split plate and grommet.

The electrical connector was pushed on to the pedal until it clicked. Easy!

Brake and Clutch hoses

The hoses needed securing so as to comply with IVA requirements. Again a part made by Keith came in to play to secure the three braided hoses against the side of the engine bay. Another pair of hands was needed to fix this wit M4 screws, so Carol came to my rescue. A P-clip was used to secure the hoses to the reservoir.

Hoses secured

Dipstick tube

This had bugged me for a while! So I thought that I had better sort it. The dipstick tube was the wrong shape for the LS6 engine. So using a pipe bender, I carefully reshaped the tube to avoid the headers and HT leads. Once it was the right shape, the tube was secured with a P-clip to the coil frame, after adding some rubber tubing to make sure that the tube would not move. It was fairly easy really. Don't know why I had kept putting it off.

Dipstick fitted and secured to coil frame

Foot well Extension

Now it was time to fit the foot well extension. Again Carol helped, as my arms were not long enough. The extension was simply bolted in place, where it had been trial fitted before. I did apply some silicone to make sure it was sealed, both inside and out.

Not the prettiest of jobs, but hopefully effective

Tail pipes

Tail pipes

A simple job that took a long time!

The principle is very simple, but the practice took a bit of fiddling. Getting the tail pipes over the central pipes is not so easy. The end of the tail pipe is slotted, but it still would not fit. So I filed the outside of the centre pipes, the inside of the tail pipes, used a crow bar (gently) on the insides of the tail pipes and applied a small amount of Vaseline. Eventually they went on.

The tail pipes are clamped by the rear fixing that holds the central pipes. The pipes were tightened in place and the centres of the Cherry Bombs measured to make sure that the pipes were positioned equally from each side. An 8mm hole was drilled in the boot floor to take the stud from the bobbin for each pipe.

Off side tail pipe fixed at front and with bobbin at rear

Tail pipes/Cherry Bombs in place

Boot carpet

The carpet was cut around the filler neck of the fuel tank. Next the fuel filler fitment was removed from the body. Then the hose that joins the tank to the filler was cut to length. Whilst I was at it I made up an earth wire to go from one of the bolts that secures the filler cap to the sender earth.

Hose, clips and earth wire can be seen

Fuel tank

I have ordered the nylocs and button head bolts for the fuel sender. So no other progress yet.

Engine compartment

Engine compartment

Today I completed the heater hoses, with the exception of two jubilee clips that I need to get. The hoses were not long enough, so I had to add short lengths into the hose runs.

Heater hoses in place, less two jubilee clips

Next the air temperature sensor was fitted to the air intake duct (the stainless steel tube). This required a grommet that would take a 12 mm sensor. I found that warming the grommet up in hot water helped with this.

Sensor fitted through grommet

Then the brake and clutch lines were coupled up to the junction point on the bulkhead. The male parts of the hose were coated with a small amount of Loctite 572. The hoses will need securing with a tie wrap or similar at a later date. The Loctite was also applied to the connections on the inner wing.

Brake and clutch hoses connected

Gear lever

The gear lever hole was enlarged a little to make sure that all gears could be selected. The escutcheon was used to mark out where the gear lever gator would go. I needed to keep well within this area.

I also taped up the loom run with racing tape in the passenger compartment. Not sure that I needed to do this, but it looked tidier prior to doing the carpets.

Gear lever hole enlarged and loom taped

Preparing to fit the body

Before I can put the body on, I needed to do a few small jobs. These will be easier now than when the body is on. Some must be done before the body can be fitted e.g. grinding down the mountings, cutting the recesss for the air intake, cutting out the hole for the gear lever etc, others can be done after, although it may not be as easy!

Had a chat with Andy at GD for any advice. Received some good tips.

Edit: Do fit the loom before you fit the body or at least connect the speed sensor, the reverse light switch and the starter motor. It is so much easier at this stage.

Now I just need to prepare for the day!

Mountings

I couldn't help taking a few photos of the chassis, before it gets covered with the body. This was one of the reasons that I went with Gardner Douglas. The engineering is miles ahead of the competition. No wonder people praise the handling of this car.

Rear three quarter view of chassis 

Front three quarters view of chassis

The rubberised body mountings, where the transmission tunnel splays out, need the top edge grinding to an angle to help the body sit on the chassis. Also I have checked that the mountings are sitting flush with the chassis. The mountings will be lubricated with Vaseline to help jiggle the body in to place.

Top mounting filed down. Note that this mounting does not have a screw thread 

The mountings were lightly sanded to take off any sharp edges.

Lightly sanded mounting

The rear mountings have been marked out in the boot to show the centres of the two mounting holes.Mine were 532 mm from the centre of the car to the centre of each mounting. The holes will be about 20 mm up from the floor of the boot apparently.

Air intake cut out

The lip and hinge mounting point needs to be shaped to allow the air intake to fit up into it. The area to remove was marked up centrally on the body. The Dremel with a sanding tube came in handy here to grind out the GRP. The air intake was offered up regularly to check the cut out.

Cut out at front of body

Under sealing area ahead of radiator

The inner wings were not undersealed when the wheel arches and nose were done. At that stage I didn't know where the lines should go. I used the mounting holes on the inner wings to determine where to put the masking tape, prior to applying the underseal.

Final bit of underseal!

Gearbox oil

Yes, this is automatic gearbox oil, even though it is a manual! Tremec recommend AQT oil. It is easier to fill the gearbox now than when the body is on.

Filling the gearbox with AQT

Gear lever hole

This needs cutting out in the transmission tunnel, prior to mounting the body. I used the mounting holes as reference points to locate the centre of the gear lever hole. This is towards the nearside, but once the gator and escutcheon is fitted it will look central. Once marked this was cut out using a hole cutter.

Gear lever hole in transmission tunnel

Footwell extension

The footwell extension was rubbed down, after I had applied some more gel coat to help get a better finish. The fixing screws will need shortening to tidy it up a little.

Horn

The horn wire is on the nearside at the front. Fitting was a case of drilling three holes (the compressor and two trumpets) in the chassis and fitting rivnuts. The brackets were fitted to the rivnuts using button head screws and then the compressor and trumpets were fitted to these brackets.

Horn fitted to chassis rail

Boot carpet

Now that the reverse and fog lights were fitted, I could fit the piece of carpet at the back of the boot. This went under the striker plate, which was bolted through the floor, before the carpet was glued down (not glued yet). The striker plate does not go down to the floor, so once the carpet was in place I made up some spacers out of the spare aluminium bar that I had used for the radiator.

Piece of boot carpet at rear fitted - wrong way round!

Piece of boot carpet fitted - right way round.

Odds and ends

The reversing light wire on the offside of the gearbox and the loom need connectors attaching. The existing connection on the gearbox was removed first.

Connections on gearbox for reverse light

The speedo connection from the loom will need a Delphi two pin waterproof connection adding - I hate making up those things. I will need to order this.

The rubber bung below the reverse lockout on the nearside was cut down and then a plate made to secure it in place.

Plate securing bung on gearbox

Surplus vacuum take offs were blocked off with button head bolts and Araldite adhesive.

One of the surplus vacuum take-offs blocked

Preparing for body fitting

I have been told to remove the radiator frame and, after slackening the lower bolts, tilt the radiator back a little. This will stop the body fouling on the chassis at the front. A bungy helped to hold all this in place.

Radiator frame removed

Small but important jobs

Loads of small jobs to do. Feels great to knock them off the list!

Coil packs

Re-fitted the plug leads and coil packs today. I have fixed the brackets to the rocker covers using M6 16 mm button head screws. The holes in the rocker covers that were not used had M6 12 mm button heads inserted to finish them off.

Coils and plug leads fitted

Exhaust clamps

I was not happy with the front and middle exhaust clamps. They hung down too low and so would reduce ground clearance and the exposed threads were an invitation to make contact with the road. Even if I twisted them around, I couldn't gain much ground clearance without coming into contact with the chassis. As we have quite high speed bumps on our road (higher than the legal limit of 4"), I needed to make sure that the ground clearance was as high as possible.

Standard brackets hang down too far

I bought four Mikalor exhaust clamps from Westfield Fasteners to replace the standard clamps. Not cheap at £18 plus p&p, but worth the outlay. The photo above shows the before view and below shows the after views.

Almost flat clamps (Mikalor)

Front clamps fitted

Gearbox mount bolts

Replaced the two bolts gearbox mount bolts with 10.9 grade bolts. The others had lost there edge from being put in, thread locked and taken out a few times.

New gearbox mount bolts

Brace bars and cooling

I refitted the front brace bars, the radiator support frame and the radiator. This should have been really easy, but for some reason the bolts took some inserting in the brace bars, before fixing with nyloc nuts.

Brace bars, radiator support frame and radiator in place

Once the radiator support frame was in place, I trial fitted the header tank and hoses. This was an easy job and very intuitive. I have used black silicone hoses with W4 clamps (stainless steel). I replaced the supplied air intake zinc plated clamps with four 100 mm W4 clamps. The radiator will have to come off for the fan to be fitted.

Hoses and header tank trial fitted

Idler pulley

The idler pulley is not used on the GD, so I removed the bracket and pulley.

Idler pulley on right

Idler pulley removed

Transmission tunnel cover

The transmission tunnel cover needed a hole cutting out for the gear shifter. First I marked this out by measuring the position of the shifter, then drawing a circle 65 mm in diameter. My chassis is a Euro, so the sponge rubber was in place, therefore the hole was cut from the bottom side of the panel.

Put away the Dremel for this job. I broke a cutting bit. The hole was cut out using a jig saw and then tidied up with a half round file.

Hole cut in transmission tunnel cover

Clutch hydraulics

A smear of Loctite 572 was applied to the clutch pipe connectors (there are four surfaces to be treated) before they were connected to the block. The block was dismantled to allow the pipe connectors to be nipped up. The rigid brake pipes from the chassis were already in place.

From left to right clutch bleed, clutch feed, brake pipes x 2 

The two braided clutch pipes were strapped together with a couple of plastic tie wraps.

So a load of easy/small jobs done and out of the way.

Cobra exhaust

New Year's day (happy 2016 to all readers) and another few hours in the garage to tackle the exhaust system.

I laid out the various parts of the exhaust system so that I knew where to fix them. The system consists of various tubes, catalytic converters, a balance box on the central pipes, plus two Cherry Bomb silencers. I have already fitted the headers. The Cherry Bombs (silencers!!) will be fitted later, once the body is in place. The diameter of the Cherry Bombs is so big that I could almost park the every day car in them!

Exhaust system, less headers, laid out

What I realised after initially assembling the system on the chassis was that the gearbox mounting plate, which also acts as a point from which to support the exhaust system on my car, had been mounted (note how I don't take any blame here) on top of the chassis lugs (logical place?). However, it should have been mounted below to avoid the pipes touching the chassis - not the best engineering solution I have seen, but the four high tensile bolts should be fine as the weight of the gearbox tail and the exhaust system are not massive. Nothing about this location in the manual, so it was trial and error, mainly the latter.

Gearbox mounting plate above the lugs

Also, I had to open up the exhaust mounting hole a little to fit the threaded part of the bobbin from which the exhaust system is supported. So the mounting plate was removed yet again and bolted to the chassis from the underside. This time it was a little more difficult to get out, as the exhaust pipes were in the way! 

Gearbox mounting plate moved to below the chassis

By moving the bracket to the underside of the chassis it moved the exhaust mount about 12 - 15 mm lower, so giving clearance to the chassis. Heat Resistant silicone was applied to the system where the pipes joined to reduce any risk of blowing (hopefully).

The rear of the exhaust system was located using reinforced rubber and six bolts (as supplied by GD), three bolts (with shake proof washers) locate into the rivnuts in the chassis and three bolts go through the bracket and the rubber mount, secured by nyloc nuts. The rubber mount needed trimming to size and holes drilling.

Rear view of exhaust before rubber mount fitted

The bracket supplied keeps the pipes the correct distance apart and helps to locate them. This is only fitted hand tight, so was not supposed to be in the right location as supplied. Drilling the rubber is interesting. It seems to self-heal after drilling!

Rear exhaust mount fitted, the six fixings can be seen

Now all the clamps were tightened up to secure the system in place and the oxygen (lambda) sensors were fitted into each side below the headers. These will be wired in later.

Exhaust clamps below a header and with the lambda sensor fitted