Sorry for the length of post but would appreciate your thoughts on my "challenge"

Last year I looked to purchase a '97 XK8 and was told by the previous owner that his mechanic said that the "engine was done". Upon review the engine ran extremely well with no codes but did have a fair amount of oil in the reservoir tank. I checked the oil dipstick and the oil condition looked good (no cream) and close to the full mark. I took the car for a drive and found that there was no heat ( thought that the heater core was plugged with oil residue). The owner who owned the car for 20 yrs said that 2 weeks before he had the oil changed at the same garage and they had a new "kid" do the oil change. The car was very nice and with a very low asking price. I bought it thinking that it might be that the "kid" might have accidentally put oil in the coolant, a leak in the tranny cooler in the rad or worst case a blown head gasket. All of which I thought I could handle.

After delays due to weather and COVID I now began working on the car. I flushed the cooling system with water and dishwasher soap and it cleaned up quite well but a slight brown oily film on the top of the reservoir kept appearing. I disconnected the trans coolant lines from the rad and pressure tested the cooler in the rad with no apparent "bubbling". I then decided to remove one of the cam covers to check the timing chain tensioner condition and found that the originals were still there and missing one of the slippers. At this point, I decided that it probably was a head gasket issue and might as well get to it as half of the work needed to be done anyway in replacing the guides, chains and tensioners.

Heads are now off and there is no signs of leakage at the any of the sealing areas let alone around the high pressure oil ways. I had the heads checked today for flatness and all is good! I am now at a bit of a loss with what to do. I am now thinking that there might be a cracked head or block? Are there places where the bottom of the Cyl block and base place where a seal is leaking?

Your thoughts and suggestions will certainly be appreciated.

 

Canuk - hopefully someone will be able to offer assistance -

 

Hmm, no heat likely means the heater pump is no longer running. Now is the time to test it, and remove/fix it. The heater valve should also be disconnected during a cleaning as it defaults open. A "theory" is that your heater core remained isolated and did not see the detergent cleaning you did with the rest of the system. Maybe the oil residue is coming from there. You can of course clean the heater core separately and find out if you collect what you flush in a container.

Best of luck, keep us posted.

 

+1

Overheat with the Jaguar V8 is a major problem - lack of heat is an inconvenience.

I think fmertz has nailed it supecting a failed heater pump.

Graham

 

Just disconnected the heater core inlet and outlets, blew out with air .... Oily antifreeze. As suggested the continual oil contamination might have/probably been coming from the heater core/valve and pump. I then took a remote 12v source and checked if the pump would run ...Yes; I can hear it running! I will be changing the octopus and heater hoses and will now check the control valve. Is it just an on/off valve?

The main problem that I have is finding the source of the oil in the coolant. As I previously described, I have checked the tranny oil cooler, head gaskets look good on removal (flat heads). Am I missing something or should I just put the heads back on, reinstall and go with the " kid put the oil in coolant" theory. Just doesn't feel right not to do everything I can before taking that approach. Is there much history for these cars of cracked heads or blocks after 23yrs with no incidents of overheating?

Thanks for your responses to date!

 

The water valve on the firewall is spring loaded open and is electrically closed when you turn on the air conditioning to prevent hot coolant from entering the heater matrix.
I had a problem with getting hot air when I selected air conditioning. I put the end of a pipe on the valve and tapped it with a hammer. Valve works fine now.

 

Did you check the oil cooler mounted to the front of the engine as part of the oil filter assembly?

 

I do not think that the '97 xk8 has an engine oil cooler.... Am I correct?

On the heater front... I think I found the culprit for the no heat. The oil in the coolant has made the seals in the control valve swell and inoperable and stuck closed. Are there any replacement rubber seals available? New valves are $$$$$!

I pressure tested the tranny oil cooler and it held pressure at 15 psi. I am still at a loss for where the oil is coming from. Without any new ideas maybe I will just put it all back together and hope it was the head gaskets or that the new "kid' at the garage mixed it up.

Has anyone have thoughts on using the "permatex high temp copper spray a gasket" on the head gaskets? I have used it in the past on cast iron engines with good results. Thoughts?

Thanks!

 

The AJ26 does have an oil cooler, however it does not use the engine cooling system, so that cannot be a source for oil entering the cooling system.

Do not use any sealer on the head gasket(s) unless directed to do so by the workshop manual.

 

Be careful,,, but remove the thermostat, put the heat on full blast face, then defrost and stuff, and continue to flush with water and dish washer dish soap. Seal system, fill, flush. Fill flush a few times... Use a hose and lots of water.

A few days ago I swapped and engine and must have cracked the fitting in the rad which mixed a TON of coolant and tranny fluid. Wanna talk about tears... Anyways,,, it takes a lot of water, warmth and heat,,, and a lot of time to get the MESS of oil out of a coolant system...

If it was tranny fluid it would be a PINK strawberry milkshake btw.

How the oil got in there,,, might forever remain a mystery.


Damn them shop boys, lol

 

Just to post how I made out. As you remember I purchase this car with oil in the coolant last year. I fianally got the engine back together with new head gaskets, timing chains etc. I took the opportunity to rebuild the heater pump and changed the heater valve ( seals were swollen from the oil). Octopus and other hoses relaced as well as coolant pump/ stat housing etc.

The engine runs great and after the intitial test run for approx 10 miles it looks like there is no oil in the coolant! Either the head gaskets had a leak that I couldn't see visuall or the seller of the car was right when he said that the "new kid at the shop put oil in the collant" at the last oil change.

Just wanted to let you know what happened and to thank all of you for your input. Now to fixing the convertible top that isn't working!