XJR6 head gasket replacement .. please check and advise
 

Hi all,
I just pulled the head off from my XJR to replace the head gasket due to white smoke at the tail pipes.
After the head was removed, there was small amount of coolant found in the last 2 cylinders (close to the fire wall) as shown below.
However, I was looking at the gasket and couldn't figure out if the gasket has shown any sign of damaged.
I don't have much experience on checking head gasket would appreciate it if someone can take a look at it and shed some light on it.
https://cimg9.ibsrv.net/gimg/www.jag...f9bc7dd441.jpg
gasket top
https://cimg0.ibsrv.net/gimg/www.jag...91f6a92fd0.jpg
gasket bottom
https://cimg1.ibsrv.net/gimg/www.jag...57cfe3de4f.jpg
cylinder head
https://cimg2.ibsrv.net/gimg/www.jag...98b49bc018.jpg
cylinder block


Thanks

Cheap thing to do is go forward and replace the gasket and check

Care on bolt torque pattern / sequence and accurate torque wrench

Next step more expensive

Engine overheat ?

The car was not overheated, the blowing white smokes occur all in a sudden a few years back... I parked it until now to address the issue. The head still in good condition without wrappage. Got the new head gasket kit and waiting for the new head bolts to continue.

03-1-13A Cylinder Head Bolts.pdf (jagrepair.com) :icon_dance-disco:

Intercooler coolant leak ?

The wet 2 cylinders only may be explained by other factors in the intake draw and cylinder combustion breakdown

intercooler leak can be repaired by J - B Weld

It is good to know the bolts are reusable. The bolts are original on my car and no sign of reused. Thanks

During the tear down, I found coolant in the intake manifold and i can't verify the leakage at the intake coming from the supercharger inner core since no leakage (please see below leakage test result)
https://cimg4.ibsrv.net/gimg/www.jag...5625f5000.jpeg
Coolant inside the intake (supercharger inter cooler core), the supercharger elbow removed from the intake.
https://cimg0.ibsrv.net/gimg/www.jag...e55219fbd.jpeg
Coolant found at the intake.
https://cimg2.ibsrv.net/gimg/www.jag...536786de8.jpeg
The breather hose inlet to the throttle body input (i.e., intake of the supercharger) shown sign of clean path instead of oily.
https://cimg9.ibsrv.net/gimg/www.jag...0fe6b5bc27.jpg
Pressure test the inter cooler on bench: Plugged all the outlet and pressurized the system to 19 psi. After 4 days and no sign of leakage (i.e., 19 psi)

" Pressure test the inter cooler on bench: Plugged all the outlet and pressurized the system to 19 psi. After 4 days and no sign of leakage (i.e., 19 psi) "

Both the inlet air after compression and the coolant will be warm as you drive expanding the intercooler to open a leak

Cardboard box and heat gun to fully with a saturation / soak time to heat up for test

good point. I will heat it up to simulate the actual condition for the further testing. Thanks

I have yet to read of an XJR with a blown head gasket, and it sounds as if yours doesn’t have one either. I would button the head back on asap with a new gasket.
The intercooler may well have a leak , and as has been suggested, pressure testing would be a good idea. For sure, any leak in the heat exchanger would find its way into the intake and the engine.

Thanks for the feedback.
At the moment, both the head gasket and the intake need to be addressed. Based on the evidence, the intake appears to be leaking and could be the main contributing factor of my xjr6 smoking problem and may well be causing my head gasket failure... not in terms of low compression, but actual coolant was sipping out at the heat and clock interface towards the end of the engine block after the smoking incident occurred. It seems to be straight forward that the core of the intercooler inside the intake is leaking source. I am trying to verify the failure point in the intake...see it to confirm it.

What has done so far: I took the intake out of the car and bench tested the inner core by plugged the inlets and pressurized with air to 20 psi (assuming intake at -ve pressure of 5 psi and 15 psi from the coolant). However, the air leak down didn't show any degradation after 4 days (i.e., maintain 20 psi). Parker7 mentioned that hot coolant test would be the worst scenario to check for the leak down. I redo the pressurized test with the intake filled with coolant, then pressurized it to 25 psi, use a heat gun to blow hot air thru the intake duct opening until the internal (core) temperature and the external (housing) temp has about 20 degrees difference (i.e., to ensure the system is temp soaked).
Findings: As the system was heating up, the pressure increased to 31 psi at 175 degree F (internal core). The pressure reached and maintained about 31 to 32psi while the core temp reached about 190 degrees. At that temp, i start smelling coolant but still has no active leaks. Continue heating the system, coolant smoke started to come out since the boiling point of the coolant is above 200 degrees. However, when i removed the heat, the smoke stops almost immediately and still has no coolant leak out. I stopped at that point.
My question: did i stressed the system to induce the smoke? or the hot leak down test condition still is not the worst case.
Anyway, I need to replace the intake. During the tear down, i found that the car was put together with stout materials and well-made. you just have to know how to get around to make the repair more efficient especially this supercharged X300. Very tight space!

It certainly sounds as if you have stressed the intercooler far enough to rule it out as the cause, and like with the head gasket, I have never heard of an intercooler failing in such a way.
If I have understood the situation correctly, you are trying to chase down a smoking problem you have been told about rather than witnessed first hand? Given you have the head off, it might be worth a leak down test on the valves before putting it back on, although again this wouldn’t be a common problem area. Thereafter it might be a case of reassembly and starting her up to see if the symptoms persist and looking for fresh clues if they do. To reiterate, the head is not a problem area generally, nor the intake manifold.

The blowing white smoke situation started a few years back when i was starting the car in one morning. The incident occurs all in a sudden, during warm-up for a few minutes, i heard a burst of noise under the engine bay and shortly after, a small puddle of coolant found on the floor in the area between the engine and the transmission housing area... white smokes start coming out from both of the tail pipes... checked the engine bay and no active leak or any wet spots. Coolant was clear without engine oil. I didn't have time to look into the problem, so the car was parked since then. The reasons i wanted to verify the cause or understanding the cause before reassembly is to avoid another tear down.

I assume there are 2 ways the coolant can get into the intake:
1) Intercooler internal leak... this will directly put coolant down to the head.
2) Thru the breather host then enter the throttle body to the intake of the supercharger... the coolant/air mixture will blast into the intake.
https://cimg2.ibsrv.net/gimg/www.jag...536786de8.jpeg
The picture above was taken with the supercharger cover removed expose the connection of the breather hose to the head... looks like a trace of coolant path thru. Is it possible that the coolant got sucked from the head to the breather hose?

Was it definitely coolant on the floor? Could it simply have been water? The reason I ask is that the drain from the air conditioning evaporator tends to deposit water on the ground around that area .
You also say that the white smoke is while the car is warming up. Does it go away once the car is warm? Did you need to keep topping up the coolant?

Hello from Sunny Venice,Florida. Have you tried watching the interior of the throttle body where the two small heater hoses go thru on the bore? Jaguar had leaks on another model there.

Thank you.
Larry Louton

Larry is mentioning 2 small 3 / 8 th hoses that pass through the throttle body on the bottom for the normally aspirated TB

Your supercharged TB is oriented / installed differently

It functions as a " carburetor ice " heat and you can road test it with the 2 lines capped off above say 40 degrees F outside air temp and low humidity

TB bench leak test would work also

At the very beginning, I thought the white smoke was consideration related, however, after the car warmed up, the white smoke gets thicker and as i increase the throttle, the white gets plenty more. The puddle on the garage floor seems to be coolant but didn't show to be an active leak.

I was looking into the possibility of leak could be from the blanking plant located at the back of the cylinder (i.e., the plate held by 6 bolts facing the firewall). I removed the blanking plate, resealed and reinstalled it. Run the engine at idle... active coolant starts to leak at the seams between the head and the engine block towards the end of the cylinder head on the exhaust side. At that point, the head gasket indicated to be compromised and in need of the replacement. I then started to the tear down and found coolant at the intake manifold... this is where i am now.

Thanks Larry.
Based on your feedback.
The Coolant leaks to intake issues expanded to as follows (Ishikawa approach...aka fishbone diagram):
1) intercooler core leaks
2) thru the breather hose to the throttle body then thru the supercharger to the intake
3) the coolant leak from the throttle body

XJR6 coolant hose connections are located at the bottom of the TB, I removed the TB and put it on bench, clean it up with throttle body cleaner.
I then hooked up to the compressor as shown below and pressurized it to 21psi. No leak was found.
https://cimg9.ibsrv.net/gimg/www.jag...03152bec30.jpg
the coolant hoses connection located at the bottom of the TB.

Thanks all for the feedback.

At the moment,
The coolant found at the intake issue can be contributed by the following area:
1) Intercooler core leaks
2) Coolant from the cylinder finds its way thru the breather hose to the throttle body then thru the supercharger to the intake
3) Coolant leak from the throttle body

Tested:
1) Benched tested the intercooler and found no leaks
2) Head gasket was found to be compromised with active coolant leaks... not sure how this affecting the coolant to find ways to the intake?
3) Benched tested the TB for leaks and no leak was found

Next:
1) I will install another intake (a used one) and will be sanity checked for leaks before the install.
2) Install a new head gasket, a new blanking plate gasket and all the gaskets provided with the gasket kit
3) Install the TB as is
4) Install an oil catch can between the valve cover breather and the Supercharger intake

Please advise if there is anything else that i should look into before the install. Thanks.