An update on this saga with coolant loss.

I was able to remove all the round ferrule things in the coolant passageways, and got three of the five filler pieces out of the slots between the bores (they turned out to be brass too). However, the last two were stuck fast and I could not move them. I therefore decided to remover the engine, strip it back to a bare block and have the machine shop remove the brass infills and mill the block face true again.


Block stripped

It took me about a week to strip the engine down, working in the cool of the mornings. Block was at the machine shop for a little over a week (he's always busy) and then it took about a week to rebuild it all.n I discovered that the mains an big ends are + 10 thou' so someone has been in here before. All the bearings and journals appeared to be in good condition.


Block skimmed

Ready to re-fit


After re-fitting the engine, I used a pressure tester to pressure up the cooling system with air to 6 PSI. It maintained the pressure and there were no signs of leaks (no hissing). I then filled with fluids and started the engine again. All seemed fine with good oil pressure (better than before, probably due to replacing the o-rings in the feed pipes etc). After checking the timing and a few runs, I checked into the bores with the endoscope, and this time found a few drops of coolant in #05 cylinder. (Previously it was #01, then after skimming head it moved to #03, now after skimming block #05).

I then added 2 cans of Liqui-Moly Radiator Stop Leak. Following that, I checked into the bores after the engine cooled following a run and did not detect any further coolant seepage for several days, however, the coolant level was going down after each run. I pressure tested the cooling system to 10 PSI and could not see any seepage.

However, on Monday this week I checked again into the bores and found more seepage into #05:


Coolant drops in #05

I checked on the coolant capacity spec and see it takes 18L. The Liqui Moly says it treats up to 7L per can, and I added 2 cans, so I thought perhaps I had used too little, I therefore added 2 more cans yesterday and went for a run. I also re-torqued the head with the engine cold and each nut went down about 1/8-1/4 of a turn. On the way home, the low coolant light came on again. After it cooled down, I checked the level and it used about 1L again.

So the problem remains. This time when I re-fitted the cylinder head, I coated the gasket with copper size. To be honest, I was not very impressed with the copper size, as the first attempt to use it, when I picked up the gasket, the copper started to peel off. I removed it all and sprayed a new layer on each side and left it 2 hours to dry, then fitted the gasket and the head. I am now wondering if it is possible that some of the copper size peeled back unnoticed as I fitted the head, thus leaving slight high and low spots.

I can't think of any other reason for this to have failed again. With both head and block skimmed, new head gasket, new studs, washers and nuts holding the head to the block, it surely ought to be good now?!! Before torquing down the head, I checked that all the (new) nuts did not bottom out by ensuring they went all the way down to the top of the head with no washer in place before fitting the washers and tightening up.

I have one more new head gasket in stock, so I can try once more with that. I am going to run the car for a couple more days first though, just in case the Stop-Leak fluid gradually becomes more effective with a few runs. Does anyone know if this is the case?

 

Andy
That is a lot of coolant. I think the first thing to do is to pressurise the cooling system using your pump apparatus to about 15 psi and see if any coolant leaks can be seen then. 6 psi is not enough to show up a leak that only happens when the engine is hot.

 

I can’t get the pressure tester to hold more than 10 PSI. At higher pressures it leaks from the cap where it fits onto the expansion tank

 

BUGGA.

I doubt its the head gasket or block.

Reasons:
If they were leaking you would have combustion pressure IN the cooling system, which you clearly do not.

The only place I can think of quickly is:

Inlet side of the system, as in Inlet Tracts, Water Rail, etc, as there is NO compression pressure in there.

Pressure testing the system to 20psi, and look in side these tracts etc for telltale signs of coolant.

Head off again, find someone, or make, the proper jig to block the passages on the head face,and pressure test that head, heating it up carefully with a gas torch, and see what is found.

I have never had success with sealants and coolant, they simply never worked well together. Most require caustic type flushing, clean water, and then sealant to work, but that is info from 30 years ago, maybe things have changed somewhat.

 

I am fairly sure that there isn’t a fault in the head itself or inlet manifold as the problem keeps moving every time I try to solve it! That is from cylinder 1 to 3 to 5.

I think that there have been 2 concurrent problems, the first being a leak from head to inlet manifold. I am confident that is now cured with the welding and machining of the manifold.

The ongoing problem is coolant seepage into the cylinder(s). I thought that fixing the local bodge with the slots etc being filled in would cure this.

As the engine is now back to standard, I think my last hope is that following the advice to use copper size on the gasket, and to add a ring of sealant around the studs where they emerge from through the block might have been the area where a problem is recurring

Next week I think I will remove the head again and replace with dry new head gasket, and put sealant at the tops of the studs where they emerge at the top of the cylinder head instead of at the top of the block before fitting the head. Maybe the sealant I used there caused high spots.

All these things have been after reading advice on this and other forums. It is hard to decide which advice is good sometimes!!

 

Andy
I think Grant's points need thinking about a bit further. The amount of coolant in the photo is quite large. If it were coming in through the head gasket I think it would have been expelled via the exhaust as steam and not be obviously sitting there in the cylinder, and I believe the cooling system would have been pressurised most noticeably.
While I do agree that a straight gasket and no dressing is a good idea, I believe before doing anything further you would do well to get the head and manifold assembly pressure tested. Engine places have special rigs that can test heads for the integrity of both combustion chambers and water passages, and do the same for your water-jacketed manifold.
If your sealant is causing the head gasket to not seat properly, then pressurising the coolant will show that up, so fixing the test cap is perhaps also important. In my rather limited experience (which I hope to remain limited!) of head gasket failure, any combustion chamber problems push coolant outwards from the combustion chamber, rather than suck it into it. Hence the likelihood, still, of an inlet manifold problem, or some sort of water jacket problem which only a pressure testing will reveal.

 

I remembered on seeing this thread again, that there is another path for coolant to get into the inlet manifold. The heater valve on the bulkhead is operated by vacuum, and that vacuum can only be generated at the inlet manifold. So there is a connection from the valve to the inlet manifold. If the diaphragm in the valve is split, coolant on the other side can enter the vacuum line and end up in the inlet manifold. So it might be worth testing this by removing the vacuum line to the heater valve, also inspect the line for the presence of coolant

 

Thanks for the contributions, always gratefully received.

I think the coolant is coming in via a gasket seep and being expelled as steam via the exhaust. I have been using the endoscope to look into the spark plug holes after the engine has cooled down following a run, so I think that when it sits having been turned off, the pressurised water system is leaking a few drops into the cylinder.

There is no longer any sign of coolant in the manifold.

The heater has long since been disconnected as it is never required in this tropical climate.

Before removing the head again I will try again to pressurise the system to more than 10 PSI with the test kit and see if I can see leaks anywhere. The tester is supposed to be able to go much higher than that so maybe I need to modify the seal on the cap.

My local machine shop does not have any pressure testing jig….it is not like the sort of place you would encounter in Europe etc!

 

I have just pressurised the coolant to 10 PSI again (failed to get it to go higher as it leaks at the cap still at greater than 10).




Pressure tester on the cooling system

With the endoscope down the spark plug hole of cylinder number 5, I saw small drops of coolant falling into the cylinder from the top. This was with valves closed, so the leak is at the head gasket again.

Next week I will remove the head for the fourth time and try again. I am busy for a few days building a shed and want to finish that before I get stuck back into car work.

Oh well, it’s only time and money I’m spending. Just wish I could get this issue resolved once and for all. It ought not to be this difficult!!

 

Well found. Can you see with the scope where exactly the coolant is entering from?

 

No I can’t see exactly as I can’t look back up from inside the cylinder with the endoscope.

Actually there are a few little mirrors and things that came with the camera so maybe I could try to rig up something.

But I think head has to come off again in any case. It’s enough to drive one to drink. Hic!

 

Just a thought. Are you sure that all the head bolts are clapmping? that any are bttoming, jsut shrt of applying pressure

Install with a new gasket. some say the copper spray is a good thing, others not so much. I used it on my last engie., A flat ead ford V8. knwn fr seepage issues. it worked fie. lucky me.\\Teh run the gine to temp; retorque the hed bots.

I can think of three sources for water to enter the combustion chamber. Intake. Gasket . Engine bb;ock. A crack in te botre of number 5!! or the head? h

 

I am quite sure the acorn nuts are not bottoming out as I have checked that they all screw right down to the face of the block without a washer fitted, then fitted the washers before torquing.

The fact that the problem keeps moving between cylinders after each attempt to resolve it seems to me to indicate that the problem isn’t a crack or flaw in the head / block casting, as that would always show the fault in the same cylinder.

Therefore I think it is a gasket issue again. I have bought my gaskets from SNGB and David Manners. They look identical from each supplier. Does anyone have any suggestions for an alternative head gasket supplier, perhaps one that is thicker than standard?

 

Another thoght!!!!

The sequence of batteening down the head. Begin in the middle and work outwards. some cunsel ding it in two stages of torque vlaue raher than nly one?

 

I assume the block was faced-off with the timing chest cover attached ? Has any work been done on the cylinder head, and if so, what ?

 

Yes the timing cover was attached when the block was skimmed

The cylinder head had repairs to corrosion in the coolant passages and was skimmed.

 

Last week I removed the cylinder head again for another attempt at solving this problem of coolant loss.

It is clear that the copper size was a bad idea....it doesn't appear to have adhered properly to the top of the block or the head gasket (but did stick well to the cylinder head).


Cylinders 6 and 5 with poor copper adhesion to block


Head gasket showing minimal sealing area at cylinder 5 to slot land

It is also clear tht the head gasket has an extremely small area where it can form the seal between the slot and cylinder number 5. In the photo above you can see that this is a much smaller area than from the same slot to cylinder 6. I cleaned up the head and block again and you can see in the next photo that the slot is offset closer to cylinder 5 and for this reason it is important that the gasket seats accurately. However, a trial fit of the new gasket showed that it was positioned slightly forward (towards cylinder 6):


Slot between cylinders 6 and 5


Gasket sitting too far forward, resulting in virtually no gasket over the land between slot and cylinder 5

The gasket is located by the four round stud holes that go over the short studs out the front and back of the block. I decided to modify these stud holes slightly to allow the gasket to sit further back, thus giving a better chance of sealing cylinder number 5 effectively.

I then re-fitted the head and used a small amount of sealant at the tops of the long studs under the washers to seal in the coolant.

Meanhile, I also discovered that my old torque wrench was under-torquing. I bought a new digital one and did a comparison test to determine this, so this was probably a contributory factor as well in previous attempts to cure this problem.

When I torqued down the head, the last nut stripped a thread! This was a new stud and new nut only fitted once before. I re-used an old nut instead.

Running the car again I found it was still losing some coolant. I added a double seal to the pressure tester and got it to hold 12PSI and was able to find a small leak at a hose connection (easy fix) and a leak at the expansion tank. I was able to fix that by using a soldering iron to plastic-weld the join where the two halves of the tank are bonded together. Now with the pressure tester at 12 PSI I cannot detect any leaks, either internal or external, yet the engine is still losing coolant on a run, albeit considerably less than before.



Cooling system pressurised to 12PSI

I think this is probably on ongoing internal leak that is hard to detect, and maybe occurring at greater than 12 PSI (the pressure cap is rated at 15 PSI). All four of the head gaskets I have used so far have been unbranded and look identical (2 from SNGB, 2 from David Manners). I think these are not made to close enough tolerance to cope with the slotted block (perhaps fine for the 7L non-slotted version of the engine). So for my next attempt I will be looking to source a higher quality head gasket. I will also replace all the studs and nuts once again as I am concerned about stretching of threads following that one nut stripping.

I welcome any comments from forum members. Just to be clear, with the cooling system pressurised to 12 PSI, I have also checked in the intake manifold, and there are no signs of coolant there.

If anyone has personal experience of the slotted block version of this engine and knows of a head gasket brand that has been used successfully, I would like to know the supplier. I note that SNGB do list a Payen branded gasket, so am inclined to order this one next. It costs four times the price of the unbranded one, so if cost is indicative of quality, it might be more reliable

 

Two thoughts:

1. although pretty, acorn nuts have always left doubts in my mind. dum them for common nuts. elimnate poe point of bottomong out and app;ying lttle or no clamp pressure.

2/ indeed, that sam;; sace between the bores is trobl;ing. Apparnety, it troubed a prior machonst. e trief tpo increase tht are.

3. I prefer the old tech bar trque wrench.

with the more complex wrench, one must reease tension when not in use. with constant tension on te br iside, it will lose accuracy.\\4 i think the better brand gasket may be the key.

use a machinist rule to check that area between the boress it might be lo! hence no clamp and presto, a leak.

Good luck/
ew

 

I emailed SNGB and let them know about the problems I am having with the head gasket location. They have very kindly offered to send a gasket set with genuine Payen head gasket FOC. So I have ordered another set of studs and nuts to go with it, in case the threads have stretched with the previous set. Parts are on the way now, but I will not be able to tackle it again for a few weeks as I am away at work again.

I did check head and block with an engineer's straight edge prior to assembly last time, and everything is true (which it should be as they were both skimmed).

 

i had another look at the gasket that you used. eureka. The thing could never seal!!!!! the slot beteeen the bores is misaligned. one part is fsr to thin to adequately seal. with the added metal that a prior shop installed, it might have ahd a chance.\\i predict the high quality gasket is the answer.

As to the skim. t is entorely possible to skim and still leae lows. not saying that is the ase here. but possible. but, as you did check, ina ll locations, seems that is OK.\\Good Luck.

i admaire your ersistence. i pride myself in t. but, you got me beat by a mile..

Carl