Signs of head gasket fault after a poor tensioner upgrade on a 4.0 v8
 

Hi, I have a bit of a problem with my Jaguar S-Type 4.0 V8 1999, around 65k miles done, had it since around 40k miles and since then only had to do a few minor things such as bushes, window regulators, spark plugs etc. Few months ago around October last year I made the choice to preventatively change the plastic timing chain tensioners. It is common knowledge that they can break around 80-100k miles and seeing as I was planning to keep the car longer it was a logical decision to get it done.

When the car came back from the garage it sounded good, but had a weird burnt oil smell in the cabin, as well as the engine mount/covers/bolts around it weren’t done up. To me it looked like they were in a hurry to put it back together. I took the car back after and even though they done all the nuts and bolt up there was still a smell of oil in the cabin/slight smoke from left side of the engine. After a quick inspection my uncle suggested it could be oil accidentally spilled during the tensioner upgrade, we could see small oil stains deep on the left side of the engine. It was logical that once those heated up, and dripped on the outside of the hot exhaust pipe, I might get a slight oil burning smell come through at low speeds. It was annoying but bearable, - I haven’t driven the car much in the last few months due to covid, perhaps couple hundred miles total. The smell was annoying as it didn’t go away - I was planning to clean under the engine bay with special oil cleaners. That’s until today.

I was on way to a shop. Once I got almost there (around 5-6 miles but on a dual carriageway) I stopped at roundabout traffic lights, thick white smoke entered my car through the air vents. I pulled up about 50m further, opened the bonnet to clouds of thick white smoke. Checking the oil cap and dipstick revealed extremely milky and frothy liquid, a common sign of oil and coolant mixing inside the engine, which is due to a faulty head gasket.

My question is, could this be due to the repair I had? could this be anything over than the head gaskets? The AA guy said it could be a seal on the oil cooler gone which is located in the middle of the engine? Also read on a Jaguar forum that the leaking from the side could be due to one of the engine covers not being properly installed or faulty? When upgrading the tensioners have they messed around with the gaskets? I am not a mechanic myself therefore any help will be much appreciated. Thank you!

After having spoken to a friend who's more mechanically minded than me, and showing him the tensioner upgrade procedure video on YouTube he said that the leak on the left side of the engine could be from a badly fitted seal and that's where the oil could have seeped into the tank. It would have explained the fact that I still had normal amounts of coolant + car wasn't overheating when I pulled up with clouds of white smoke from the air vents inside the car and under the bonnet.



Any idea if that sounds like it?

hi
if you water level normal, it not likely be head gasket, but a compression test would confirm all the cylinder are good
oil leaking on to exhaust will cause lots of smoke which could be the cause
quick oil change aswell just to confirm the oil ok, i would be tempted to do
a lot of time a sniff test will check head gasket ok, but I dont think that will prove unless the head gasket fail to the water system
milky residue in the oil cap, could be normal if it not been used much, as condensation can cause that if not used on good runs, but wipe it clean and check again
if head gasket had failed to water would expect water to have milky residue in and lots of milky oil when you change it
cheers
Joe

The water level is normal - I've been told it's because I stopped and pulled up so quickly it didn't manage to leak all out. You can see there is white residue inside the cooling tank. When I open the oil cap its not just a little froth, it's more like someone added 5 big scoops of sour cream right on top of the oil filler. On top of that when checking the dipstick the bottom of it is clearly milky, as if it's been dipped in sour cream quickly. When I pulled up I remember the temperature still being normal - the temperature gauge on the jag is only advisory and doesn't reflect the real temperature. I've been told as I've pulled up literally seconds later it didn't manage to shoot all the way up to high yet.

I'm more than happy to change the oil but would it show me anything? I'm pretty certain that the oil would be milky.

After showing my friend the tensioner upgrade procedure he thinks that one of the seals at the bottom of the engine that they did have to mess about with (not headgasket but some seal/gasket near the side/bottom of the engine) is gone/wasn't put on properly and that's where the oil mixed with the coolant. Any idea?

I’d suggest running some basic diagnostics. This new problem may not necessarily be related to the recent work, so be careful not to steer your results in that direction.

Hook up a cooling system pressure tester. This device looks like a bicycle tire pump and connects in place of the cap on the reservoir. With the engine off, manually pump up the system to the rated pressure and then watch the gauge. If good, the system will hold pressure. The gauge will drop off in case of a leak.

I’d change the oil for the next steps. You don’t want to damage any bearings while troubleshooting.

Do a compression test of all cylinders. This will help find a head gasket failure.

Do a test for combustion products in the cooling system. The tester I have looks like a turkey baster and is filled with a special tinted liquid. With the engine running and reservoir cap removed, you draw in a sample of air from the reservoir. If you’ve got a combustion leak into the cooling system, the test liquid changes color.

Thank you for all the helpful advice. I've spoken to the garage where I had the timing chain tensioner upgrade and they were willing to have a look, but said it is unlikely related to their work. I'm not mechanically minded just seems a big coincidence that couple hundred miles after thei work, which was poorly done and I had to come back to the mechanic to get some nuts and bolts done up which weren't done up after the work was done. Also there was an oil spill or perhaps a leak from the left side of the engine (left side while sitting in the car) that made the cabin smell awful. They put it down to a minor oil spill but it didn't go away after the couple hundred miles/few months after the repair.







Is there any chance it could be their poor work that has caused my problems?

Have the garage review their work, including making sure all fasteners are correctly installed and tightened, then clean the engine compartment to remove any spilt oil.

Report back once the garage has had a look.

Did the car have just water in the cooling system prior to the timing chain tensioner work? That should have been spotted by the repair shop and corrected, or at least you should have been advised as to the risks of doing this...

I have been a mechanic for over 40 years. I have never found an engine where there was a Large amount of white milky substance in the engine to not be coolant entering the crankcase. Jaguar and Rolls Royce are my specialty. The source may not be a head gasket, but in my opinion it is a leak into the crankcase. A cylinder leakdown test will eliminate or confirm a head gasket. You could also try a Blocktest. The kit is available from NAPA and other sources. However this will test if you are getting exhaust into the cooling system. Dont waste your time and money changing oil. You have an internal problem.


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when you say 0...is that F or C...if it is C then it would be a remote possibility of the water freezing and cracking something....if F, then there is a possibilty of freeze damage, especially if parked uncovered...some water passages are very close together, especially in the head area

Unfortunately, this kind of question is what appears when a member asks for assistance, but fails to indicate his/her general location in their profile for the forum...

0° either F or C is freezing. Water expands when it freezes and will crack a block. However if the block wasn’t cracked before they changed the tensioner and it didn’t get down to freezing after they changed the tensioner I have a hard time believing that a crack started before that Tensioner change and then let go after it was completed. Also when the shop changed the tensioner I can’t believe they would not have refilled it with antifreeze and water mix. It should be antifreeze in there now. Is there?

I would take it to a different shop first. This is a major malfunction and it’s not gonna be cheap fix. DO NOT CHANGE THE OIL YET. You may want to send out the oil sample for an oil analysis to see what metallic components are in the oil that’s in the block now. Blackstone labs is a lab I use and they are pretty good.

The first shop who did the repair will bend over backwards to say it wasn’t them and may even try to cover it up so go get an independent diagnosis from a different shop and let them know everything that happened and let them tell you where the malfunction occurred and then we can tell you whether or not it’s related to the tensioner but right now due to the timing I suspect it is due to something the repair shop did. if it is a head gasket it seems unlikely that a tensioner change process even if done incorrectly would damage head gasket but the timing of the failures is definitely suspicious

Obviously don’t start the engine

This is a tough call. Say you take it to Shop B and they determine Shop A (the first one) was at fault. Shop A may not accept those findings and ask why didn't you talk to them first? Furthermore, Shop A could now say they have no idea if Shop B caused any additional damage during their test procedures. Maybe they would disassemble a suspect area for a visual inspection when a pressure test would be a better option. But since the suspect area was disassembled there's no way of knowing the true condition at the time of the failure.

I think at the very minimum, at least talk with Shop A first and see what they say. Who knows, they may be very reasonable to deal with. We all seem to be jumping to the conclusion they will respond negatively. And if they do, there's always Shop B. Could you ever recoup any money from Shop A? Who knows how that would play out. It could get ugly.