Hi There,

Looking for some help with head gaskets seeping on my 2002 XK8 Convertible.

A little history...

Bought the car a year ago with a broken timing tensioner, car had 4 bent valves and needed a timing chain job.

Tore it down and performed the following:
1. purchased the upgraded timing chain kit - replaced all 3 chains, new tensioners, and new guides. The tensioners were the newer models not the original plastic style
2. Had the machine shop rebuild both heads - valves, guides, seals, the works
3. Purchased and installed new head bolts - didn't reuse the originals and followed the Jag service manual torque sequence and specs to the T
4. Purchased/Replaced ALL gaskets when I did the head job, from valve cover to oil pan to exhaust.
5. Running nothing but mobile1 synthetic.
6. Replaced ALL filters and ALL hoses. Replaced the coolant housing at the front of the motor and all clamps as well.
7. Only driven the car for about 3K miles since the overhaul.
8. CAR RUNS LIKE A CHAMP.

A very expensive proposition indeed as I didn't cut any corners!

Problems I need help with....
The car was leaking coolant behind the motor. $266.00 at the Jag dealer last week, I replaced the heater hose assembly. No longer leaking coolant. BUT the low coolant like comes on from time to time but the car never gets close to being hot. No drips of any kind, no sweet smells, and no heater core leaks either. Any suggestions?

Second, oil is seeping from both sides at the head gasket where the head bolts to the block. Its not a bad leak as my oil level hasn't dropped and I haven't had to add oil. Could this be bad gaskets even though they are new? As I said, I followed the Jaguar service manual & instructions. They didn't call for putting any RTV around the head bolts before installing them. I usually do that when rebuilding older GM/Ford engines. Was I supposed to?

Any ideas on how to fix these last two issues would be great. As I said, the car runs like a champ, no check engine lights, no hesitations, now misfires, etc.

Sorry for the long post but I wanted to help you guys try to help me.

Thanks in advance!!!!

 

If you didn't change the expansion tank, it could be the reason the low coolant light comes on. Make sure it is filled to the bottom of the opening. and not losing coolant. Even if it is not leaking, the float or sensor could be bad.

The sensor is pretty fragile, but my money would be on the float. After some years they tend to get "soaked" and no longer float properly. They also like to stick.

If the warning light stays on, take the cap off the expansion tank (when it is cool, not hot!) and see if you can lift the float. If yes and the light goes off, you will need a new tank. There are many threads on this common problem on the forum.

As for the oil leak, are you sure it isn't coming from the cam covers? This is a more common source of oil leaks.

 

+1 on the covers- they can leak down to the head gasket seam and then make it look like it is leaking there.

 

When head gaskets fail they usualy fail internally between the coolant passages and the combustion chamber or coolant passages and oil gallery, not externally.

 

When you say the coolant light comes on from time to time do you mean it goes out on its own accord? If it does this could also be a dodgy cap, when the system gets hot it expands and sends coolant to the atmospheric tank in your fender, as the system cools it is suppose to suck it back again to keep the level, if this is not happening correctly it will cause the symptoms I think you are describing, easiest check is to take a look at the atmospheric tank and see how full it is, should be about a 1/3 full........ Of course the float as Jag#4 has described is a good suspect too.......

As to the oil leak I would be surprised if it's coming from the head, you would have to of missed something pretty bad to of caused it (chunk missing from the head surface for instance) but I can't see it, you seem pretty meticulous in your description and I would agree with the other guys

 

Guys, thanks for the quick replies. I wasn't sure what to expect as I'm new to the forum but am thankful.

On the coolant light, yes it comes on and goes off all by itself, when I checked it last night the coolant was about 1" from the cap and the light was on.

I didn't change the coolant/expansion tank and didn't realize it had a float inside. I just saw the connector at the bottom and thought it was all electronic (i.e pressure type). Will test the float when I get home tonight. Haven't driven the car today so it should be a quick test. Is the atmospheric tank the same as the coolant tank or is this a second tank tucked in the fender? I'm assuming it would be on the drivers side fender..

With regards to the oil leak, I could see how the cam cover leak could look like a head gasket leak. I'll put the car on the lift, clean everything off and take a closer look. Maybe I'll get lucky and just have to change the cam cover gaskets.

Its particularly chilly out here today but I'll try and get to it so I can post my findings. Worst case, I'll check the oil leak this weekend.

Really appreciate the help.
Thanks again
Hany

 

The expansion tank, which has the sensor and float, is located on the LH side top near the firewall. The other tank is in the RH side fender well, but doubt that is your problem.

 

Thanks Mike,

Here's the latest... looks like the coolant sensor problem is indeed with the float. I drain the coolant reservoir and couldn't get the float to move. looks like it is gunked up pretty well. I'm going to order a new reservoir and replace it. If you guys have any suggestion on the best sources for Jag parts that would be appreciated. I need to change the front shocks and bushings out as well. Any recommendations would be great.

Onto the oil leak. Checked the cam covers, clean as the day I installed the heads. The aluminum has no signs of runs or dark spots under the lip of the cam covers. The seepage is coming from the seem where the head meets the block on both sides. No significant but a slight leak. That's the bad news... I'm going to run a compression check again and see if everything looks normal. If compression is where its supposed to be (I suspect it will be), then I'm considering adding a sealer. When I worked on Cadillac Northstar motors, the dealer/service manuals called for adding a few pellet of block sealer as part of the standard service procedure.
Is this recommended for Jaguars? I'm only thinking of trying this IF compression is all good. If compression is low, I'll spend the 14-16 hours tearing it down again.

FYI, the good news is I found a slight leak at the front of the oilpan gasket which I'm going to fix while I'm at it. Wouldn't have seen that it I didn't put it on the lift.

Let me know what you guys think or if you have any suggestions.

Thanks once again!

This site is great..