Has the engine got a coolant path in the manifold? Some carburated cars had water heated manifolds? From your photo, it looks like it. If so, then this system may be leaking under pressure, so you need to pressure test the coolant system.

 

Being as you, and the car, are in Thailand, I would remove those 2 coolant hoses, join them together with a suitable connector, and by-pass the coolant going through the throttle body totally.

That feature of warming the body is for Snow type climates, and is not needed where you are, nor down here.

 

I’ve already tried bypassing the coolant path through the throttle body (as mentioned in post #9). That made no difference. I have also tried pressurising the path through the throttle body, and there was no leak there.

Just now, I think there must be a leak somewhere in the manifold. It is clearly getting worse so maybe I’ll be able to spot it tomorrow when I remove it again, especially following Carl’s test procedure. Perhaps if there is no obvious leak I might need to find a way to pressurise it by blanking off the coolant passages etc.

 

OK, got that. Further up the supply chain then.

Only ever played with one S3 6cyl, so memory is what it is.

The coolant rail, attached to the cylinder head, and the manifold attaches to that rail, can rot out. The S2 Carby cars did that back in the dark ages.

The gasket between that rail and the cylinder head has water passages in it, so a good chance that may be the source. Corrosion in and around those passages can be bad, depending on coolant care going back 20+ years, so basically an unknown.

 

The coolant rail is bolted to the manifold and doesn’t have a direct connection to the cylinder head. So it’s looking rather like a problem in that assembly I think

 

Agreed.

 

This morning I removed the manifold again and set it up on the bench with the coolant passageways uppermost. I blanked off the small hoses and fitted large hoses to get the ends higher than the coolant passages

Then I filled it to the brim with coolant. The level remained constant and did not drop.




So next step was to block the large hoses, make up some blanking plates and gaskets for the coolant passageways and pressurise the system with a bicycle pump. I added a pressure gauge with the plan of getting to 15PSI max.

As soon as a slight pressure was present, coolant squirted out from around the front coolant passage. I then swapped a blanking plate and gasket from one of the two watertight passages. The coolant still escaped from the front one.




I therefore think that the problem is there is too much corrosion of the alloy manifold around that coolant passage, allowing it to escape past the gasket and into an inlet passage. The pressure was still very low and the gauge had barely started to register.




I don’t feel very confident about trying to repair the corroded area with chemical metal….opinions invited on that though. I don’t know of a local service where the manifold could be re-worked either, unless a skim of the surface might be sufficient. I suspect not with the fairly deep pitting around that passage. However, I might strip it down and take it to the local machine shop for an opinion.

As ever, comments and suggestions are welcomed!

 

A bodge but in the absence of a better replacement I would:

1. Get the machine shop to make up a 4mm thick stainless steel plate identical to the face of the manifold.
2. Then get 4mm skimmed off the face of the manifold (this will not fix the deeper holes but will improve matters a good deal
3. Buy some high temp epoxy and gluing the entire surface attach the new plate (suitably keyed on its mating surface) to the old manifold face and leave to set, plate DOWNWARDS on a known flat surface.
4. carefully clean the block face
5. replace manifold and glued plate using a new gasket.

 

I have seen worse.

The corrosion you see is identical to body rust. What you see is only the tip of the iceberg.

Corrosion down further could be the root cause, and when pressure is added, apart from the plate leak you have, maybe the wall thickness further in is compromised.

A decent, even half decent, machine shop, should be able to plate, pressure test etc for a final verdict.

Not sure of sa upply in Thailand, but a s/hand manifold may be better choice?.

 

BINGO!

DO I GET A PRIZE? mY SUGGESTION AS TO THE CHECKING OF THE MANIKIFOLD ON THE BENCH!!!

In my opinion, it is junk and not likely to be reliable. Evewn with Greg's oimaginative fix.

but, is a better one avaiable. too far from David Boger of everydayxj?

Or, hog it out with an end mill and get to cleanmetal. Weld in TIG. remachinwe???

Way back, My Ford V8 blew a head gasket. foolishly, I drove it a while. Ugh, it burned away iron beteween bores. A losw spot. i used an old machinist "bodge" A sharp puch. Liyylr ***** marks to raise the metal. it worked.Amazed? YUP

 

I just took the manifold to the machine shop. He reckons he can fix it with some welding up then machining a flat face.

Hope he can manage it. He’s very
good and hasn’t let me down before with jobs I’ve asked him to do.

Carl: there is a bottle of beer here with your name on it 😄

 

Drink it for me. My beer isn ow Non alcoholic! per doc's suggestion, a strong one. found a few that re pretty good. i will down one in celebration of yiour victory. It is sweet, is it not!!!

Carl

 

Yesterday I got the manifold back from the machine shop. The pitting has been filled and the surface milled flat, see photos below:


Mating face

Deep pitting repaired

I just finished putting it all back together and went for a road test. On return I let it stand for about half an hour then checked the manifold. Once again I have coolant pooling in there.I can only conclude that there must be a further problem with it, so I think I will buy the used one I ws offered last week.

 

Time for another update on this saga.

I decided to pressurise the water system and look for leaks. I fitted a bike pump to the expansion tank outlet (the one that goes to the capture tank) and pressurised it with a few pumps. Then put the endoscope into the manifold. No leaks observed there. So I took out the spark plugs and looked in each cylinder. I could see a growing pool of coolant in #01. So conclusion was that the head gasket had indeed failed. I could still not understand how water could get from a cylinder into the intake manifold though, so I consulted a very experienced (retired) mechanic friend. He says that, due to 'valve overlap' the inlet valve is momenetarily open at the same time as the exhaust valve, and at that time there is no vacuum in the cylinder. Water could get into the intake manifold at this point in time, apparently.

So off came the cylinder head. Fortunately it wasn't stuck this time - when I removed it 18 months ago to work on the valves, it tooka about a week to coax it off using 4 bottle jacks.

Some of the water passages in the head that connect to the block are enlarged to due corrosion, much like the manifold was. So the head has gone to the machine shop to have them repaired then the face skimmed. I am expecting it to be done by today or tomorrow, then I can start reassembling. I have a week do do it, as I am heading off to the Middle East for work again just after Xmas. Meanhile I pressure tested the intake manifold on the bench again, and this time it is watertight. I used a tiny smear of silicone gasket compound under the paper gasket when testing this time, and think I will do the same when reassembling, at least to the manifold side of the gasket where a few minor pits remain in the mating face.

I am hoping that the engine reassembly shouldn't give too much bother, as I replaced all the head studs last year, and all the valves were new and re-shimmed then. The valves are all still in excelent condidtion, having done very little mileage since then.

 

Bugga,

At least you found it, Better than some who go to this and still have no source.

Good luck.

 

Andy T
Just a small note of caution in regards head and/ or block skimming.
The acorn head nuts only allow a small amount of clearance between the end of the head stud and the internal end of the nut.
Skimming reduces that clearance.
I have seen cases where the nut gets thread bound just as it is contacting the head washer on the stud.
This then means the head is not torqued down to the correct pressure and results in premature head gasket failure.
My son found this had happened on a S3 XJ6 about 20 years ago. It turned out that the previous owner had the block and head skimmed.
When assembling a Jag engine I always check this after fitting the head by running the nut down on the stud without the washer until it starts to get thread bound.
Using feeler gauges you can then measure the gap and check that gap against the thickness of the washer.
If it is marginal it is time to add an extra washer.
Bill Mac
MK1
MK2
S3XJ6
X300
15 previous Jags MK5 to X308

 

Good advice, thanks Bill

I did as you suggested and all but one of the acorn nuts were able to screw right down to the surface of the head with the washer omitted. The back right one (one of the four short studs) only just went below where the washer was, so I found a thicker washer for that one. Well worth taking the time to check that.

I haven’t finished reassembling everything yet but hope to do so tomorrow morning. I would like to get the car back on the road for Xmas!

 

Andy T
Glad that the advice worked as I suggested.
Did you make your Xmas deadline?
Bill Mac

 

I finished off putting the engine back together and repressurised the water system. I did not see any coolant get into the cylinders this time. Did a compression test and all were good. Tried to start the car but it just catches and revs a bit then dies. I must have disturbed something with all the taking apart and putting back together.

Trouble is, this morning I decided to have another look into the cylinders with the little camera, and there is a pool of coolant in #03 now.

While the head was off I checked the face of the block using a straight edge and a feeler gauge, and it looked to be good (I couldn't get a 4 thou' gauge under the straight edge). So what is going on?! Could it be that the cylinder head has a crack or hole somewhere? I am struggling for ideas now. In any case I am out of time to play with cars as I am flying away to work on Wednesday, so will leave this until I get back. Last time the coolant was getting into #01 and this time it is #03 so it seems unliley to be to cracks or holes. I got the head gasket from SNGB and it is the same type as I used last year when I worked on the valves - npt a copper gasket but a black material with metal rings around the cylinders (these are joined on the bottom face of the gasket).

Any suggestions gratefully received. Perhaps I should pull the engine, strip it completely and have the block face machined? To do this, do the liners come out? And what about those slotted things between the bores?

 

Another update to this saga:

I had another look with the endoscope into #03 and could clearly see drops of coolant entering at the top of the bore at the gasket joint.




So the problem is clearly with a lack of seal at the head gasket.

I read on Jag-Lovers forum some discussion about the use of copper size to coat head gaskets. One poster stated this:

“ First, the head and block surfaces should be clean with no grease or oil on the surfaces. You are asking for trouble if you don't. Second, the head gasket is coated with coppercoat on both sides. I have used this method for over 14 years on my cars with no ill effect. I was told to do this by Jaguar mechanics when I was first rebuilding my XK140. Never had a problem. A friend of mine did not do this and had to replace the head gasket on his E-type because of coolant seepage”

This is the problem I am having, so perhaps I should try again and use copper size.

Looking at the gasket, it seems odd to me that all the coolant passage pass throughs have an orange seal ring, but none of the triangular stud holes do, yet the studs are “wet”. Surely they should have that around the edge of the hole in the gasket too?