An annoying oil leak

[IanR]

Hi Folks,

I am posting this in the 6 forum as I think more people read it than the 5/250 forum but even though this is 5 it makes no difference here.

Elsie, (my TR5), is progressing nicely since the completion of the rebuild late last year and nearly 500miles have been covered. Though I have spent quite a time attending to the usual rattles and squeaks that go with a complete rebuild I am now down to the last (I hope) few niggles.

 

Oil is leaking, (well, more weeping really) from the distributor side of the cylinder head. By this I mean that oil is exiting between the head and the block, i.e the head gasket is not making it quite 100%.

I am assuming this is due to higher than normal block pressure, (engine is much modified but not an all steel racer), CR is just 10:1), but would have expected this to be relieved through the rocker cover breather, (which in mine goes to a separate catch tank fitted with a mini K& N filter all of which is new and not blocked).

 

I have checked the torque on the head bolts and they are OK. The head gasket is by Payen, and was fitted dry.

 

Its not much of a leak but as the engine frees up and the revs increase then I am beginning to notice it more.

Has anyone experienced this and what conclusions were arrived at?

 

Thanks in advance for any comments.

[Richard Crawley]

Oil is leaking, (well, more weeping really) from the distributor side of the cylinder head. By this I mean that oil is exiting between the head and the block, i.e the head gasket is not making it quite 100%.

I am assuming this is due to higher than normal block pressure, (engine is much modified but not an all steel racer), CR is just 10:1),

A higher c/r would not cause oil seepage between the block & the head as the increased pressure is in the combustion chamber not the crankcase. Excessive crankcase pressure won’t help but this is usually associated with worn rings/bores, I would not have expected it to be a problem on a rebuilt motor unless things have either been machined or assembled incorrectly; have you checked the breather system or the flame trap (PI) is not blocked? Although the gasket appears to be sealing around the cylinders (or there would be other signs), it’s obviously not sealing around the oil galleries properly, have you also checked for any oil in the coolant? I assume the head was skimmed when the c/r was raised but did you check for signs of corrosion around the galleries on the block face & that both the head & block face were flat? I know there are different gaskets but did you fit the gasket the right way up, they are usually stamped TOP? Something is obviously no quiet right & I would be inclined to investigate sooner rather than later if it’s got worse.

[Guest ntc]

Hello IanR,

 

Richard is quite right but there is one or two points you should look out for the latest Payen gaskets are of dubious quality, and this is a common leak. If you look at the location of the cylinder head bolts in relation to the edge of the head this has always been a weak joint easy remedy degrease and clean along the joint and a slight smear of RTV Silicone tends to hold back a slight weap for quite some time. Hope this helps.

 

Regards,

NTC

[stuart]

Hi Folks,

I am posting this in the 6 forum as I think more people read it than the 5/250 forum but even though this is 5 it makes no difference here.

Elsie, (my TR5), is progressing nicely since the completion of the rebuild late last year and nearly 500miles have been covered. Though I have spent quite a time attending to the usual rattles and squeaks that go with a complete rebuild I am now down to the last (I hope) few niggles.

 

Oil is leaking, (well, more weeping really) from the distributor side of the cylinder head. By this I mean that oil is exiting between the head and the block, i.e the head gasket is not making it quite 100%.

I am assuming this is due to higher than normal block pressure, (engine is much modified but not an all steel racer), CR is just 10:1), but would have expected this to be relieved through the rocker cover breather, (which in mine goes to a separate catch tank fitted with a mini K& N filter all of which is new and not blocked).

 

I have checked the torque on the head bolts and they are OK. The head gasket is by Payen, and was fitted dry.

 

Its not much of a leak but as the engine frees up and the revs increase then I am beginning to notice it more.

Has anyone experienced this and what conclusions were arrived at?

 

Thanks in advance for any comments.

Just a thought try removing the little K&N filter from the catch tank. I tried one on my 4a when I fitted the Dellortos and had nowhere for the breather to go into the manifold I then had oil seepage from the rocker cover. Removed it and vented via a pipe down to below sump level similar to early engines and it cured the problem.

Stuart

[IanR]

Richard,

Thanks for the reply. I do however appreciate CR is not a factor in block pressure, but in the problem I have it is pertinent to lateral pressure across the head gasket. All components are newly machined including the top of the block, and the head and block were blued for flatness before assembly. The machiing is beyond reproach but even then I measured each bore prior to assembly, and pistons and rings were fitted with the utmost accuracy and precision that I could muster. I have 35 years of professional engineering experience so I don't take these things lightly. THere is no sign of oil in the coolant or indeed at this stage any noticeable loss of oil .. as I said it is just a weeping , an oily finger as it were. Flame trap and catch bottle are entiely clear and new.

Apreciate your comments though as I recognise you know more than most so many thanks.

 

 

NTC Thanks for this which seems more likely, .. I thought Payen were the best you could buy .. Can you recommend a replacement ... Richard suggested that there was as way up for gaskest but I recall that the oil feed hole os at both ends and it was not marked top ... but I may be wrong..

 

I still feel that since the weeping is all along the MU side of the block then it is to do with block pressure not the oil feed from block to head that feeds the rockers, ie the big holes either side of each pair of push rod holes. !!

 

THanks for your replies so far

[Richard Crawley]

I'd go for the gasket as ntc. suggests, either dodgy or incorrectly fitted; no slant intended. Sounds like you have a similar background to me; been involved mechanical engineering one way or another since first being apprenticed back in 1966, when we still had such an industry!

[TheSeacherMan]

I think this side of the block has the hole for the rocker feed, and the head gasket should have had a little sealing washer. This may be where the oil is leaking from.

[88V8]

I believe this is a common problem, exacerbated if there is no suction (manifold) scavenging from the crankcase.

 

As NTC said, a thin silicone bead on the (outside edge) of the gasket face seems to be the only 'solution'.

Of course, there was a reason why the block was painted black.

 

Ivor

[IanR]

Thanks for the replies chaps.

 

An interesting comment Ivor, re the scavenging from the block. So as an experiment I have just removed the pipe from the oil catch tank and reattached the end to the plenum box, to provide a similar set up to the original, and if the weather clears up round here (looks promising at the minute) I will go for a blast accross the moors this afternoon. Will report back later.

 

It looks like I am going to have to replace the gasket though if this does not work, so does anyone know of a suitable alternative to Payen??

 

Thanks

[john.r.davies]

It looks like I am going to have to replace the gasket though if this does not work, so does anyone know of a suitable alternative to Payen??

Thanks

 

Jigsaw (http://www.jigsawracingservices.co.uk/) can supply copper faced gaskets, I think. At least Mark used to use them for his race Spitfire. They were bespoke even then, so if they are still available, they can be made for a six cylinder.

Another way to avoid this is to use an external oil feed to the head. Block up the drilling from the rear camshaft bearing scroll, which may mean removing the head anyway. Put a restrictor in the ext.feed. I've seen 0.8 - 0.5mm quoted, but don't try it without some sort of restriction, or the mains can be robbed of oil flow.

 

John

[IanR]

Hi again chaps,

Went for a run over the moors this afternoon, gorgeous day if a trifle windy. Car went like a dream so either I have got rid of all the rattles or the wind noise was to high to hear them!!!

 

Well the point was to see if the quick mod I did this morning, suggested by Ivor, had any effect. Regrettably not, as another oily finger was to be had on my return (25miles).

 

So I must decide whether to live with it or take the head off, I even rechecked the head torque this afternoon on all nuts but they are now at the maximum of 70lbf ft. Ah, now then have just checked this in the white book, and also in the brown TR6 WM and both say 80lbf ft yet the blue TR5 supplement (which is what I was working to) says 65-70lbf ft so maybe that might improve things, any views??

 

John and others seem to point to the source of the oil as the feed hole through the head to the rockers, and that does sort of corrolate with the majority of the oil being at the rear on the MU side, which is very close to the oil hole. ( Mind you we are talking tiny amounts here anyway). However some evidence of oil can be seen on the flat protrusion where the block number is stamped, several inches further forward.

 

So I suppose, that it may be both oil to the head related and pressure in the block, though I begin to wonder that the latter may not be significant.

 

Any other observations very welcome and thanks for replying one and all

[Guest ntc]

 

Did you have the block crack tested so it did not look like this

[IanR]

Hi NTC,

 

Nasty! A previous 6pot engine I built was initially crack tested (by me) using the dye penetrant method., No cracks found but the block later developed a water leak just above the core plugs on the exhaust side.

This got worse and eventually the engine was removed and Magnaflux tested to find not one but 2 cracks running laterally about 8 to 10" long apiece.

They were eventualy metal stiched for a complete cure which after repainting was also invisible.

 

After that experience I had everything Magnaflux tested that I thought could be cracked so I am pretty sure the block is sound, that could, of course, be famous last words but only time will tell.. Hope you get or got yours fixed.

[Guest ntc]

Everything sounds ok then 1st point head bolts 80pounds car be stood 12hrs ie cold 2nd gasket is not marked top unless you fitted the wrong one? is there a tab at the rear ? How much is leaking ? v88's post is about right

 

ps The pic is of an engine just back from a recon thankfully not mine

 

Regards

ntc

[Lockley210]

Hi Ian

I am experiancing exactly the same oil leak after a recent rebuild, even after having the head and block checked by the reconditioner for trueness (but not crack tested)

I used blue holimar sealant on the gasket ,so was a little surprised to see oil seepage in this area of the head.

A very small quantity lies on the tab half way down the head and the side of the block on the MU side is slightly smeared after a run.

I am thinking of using Areldit to see if it will seal it externally.

Mark

[RogerH]

Hi Ian,

can't help with your oil leak but am interested about your mention of Dye Penetrant testing and Magnaflux testing (I take it you mean Magnetic Particle testing). For the Dye Pen did you use the spray cans or full immersion (workshop process) and was the block thoroughly cleaned. Who did the Mag Particle and how.

Although these are the easiest of the Non-Destructive Testing (NDT) processes they still need to be processes under controlled conditions.

I have something of an interest in NDT in aerospace applications.

 

 

Rgds

Roger

[TheSeacherMan]

 

I don't mean to offend anyone, and I don't know anyones level of expertise. However, can we assume that the oil is not coming from the valve cover? These leaks can be sneeky. I made a special valve cover seal for my car, I don't have to bend the valve cover tightening the bolts to get a good seal. That said, the problem in not the head bolt torque. If the oil is coming out ot the head and block junction, you need to remove the head to fix the problem. I torqued my head bolts when I built my engine, and have over 5k miles, no leaks there. I should however check it.

[IanR]

Hi Lockley,

Thanks for your reply, I think now that some sort of sealant MU side of the head studs is a good idea, however the use of blue HYlomar (I think you mean) is perhaps not the most suitable for this application.

I dont think either that Araldite stuffed in the joint, or maybe you mean as a gasket sealant when reseating the head is a good idea either, if the Araldite lives up to its name you will never get the head off again!!

 

Roger,

 

The dye penetrant a while back on another block was by aerosol cans and I repeated this on this block. The Magnaflux however which I cannot carry out at home, (yes magnetic particle testing is the more exact name) was carried out by a well know company in Doncaster. The block was chemically stripped and cleaned before machining and was tested before it saw any work. After machining and several weeks of 'resting' (not by design but I wanted this to happen) the process was repeated.

Insofar as I am aware the company who did this swathed the block in mag rich liquid and then inspected it under UV in a strong magnetic field though I am aware that they could have done it by the so called dry method.

 

I did not inspect this process happen, it was described to me and met my understanding of the technology at the time. I too have been involved with the aerospace industry before I retired but I suspect from a very different angle than yourself. PM me if you want to know more. Actually many companies offer magnaflux in one form or another .. Dye penetrants.. good technoloigy in 1960's... **** now except for tectonic plate boundries or the like. ( OK good for big cracks on smooth surfaces and works OK on Ali castings I do concede).

 

Cheers

[Barry]

Just a thought, have you checked the little hole in the dizzy pedestal. I had a leak there and it took me ages to work out where the oil was coming from,I fitted new seals and that cured it.

 

Barry

[smizgals]

... Richard suggested that there was as way up for gaskest but I recall that the oil feed hole os at both ends and it was not marked top ... but I may be wrong..

 

Fitted a Payen last summer, did not see a TOP mark, was advised to fit it with the shiny strips between the bores face down.

No problems so far. Was also told that this is a common oil leak and should apply a touch of Wellseal on that side, which I did not do. In the 'How to improve...' book the use of a silicone sealant there is also recommended.

Edited March 31, 2008 by Stan Mizgalski

[John L]

I trust you backed off the head bolts about half a turn before you retorqued them, Retorquing the existing position you would want much more to move than the original torque figure. Done cold.

Regards John

[IanR]

Hi Chaps,

Working on the basis that its a whole loteasier to tighten to the correct torque (I can't imagine why Triumph had increased the torque for 70 to 80 between 5 and 6 ... Oh yea) than it is to pull off the cylinder head I did this this evening. Yes I did back off the torque in sequence before redoing. Have not tried it yet but will do tomorrow hopefully. Having spoken to Neil Revington today he says that Wellseal is normally used for head gaskets in their workshop so there you go.

 

THanks again for the comments will post after tomorrow if any effect, not hopeful however.

[john.r.davies]

Ian,

Just a thought. Have you fitted an external oil feed to the cylinder head?

Is it this that is leaking, and seeping onto the rear of the head, as if between that and the block?

 

The recess drilled for the bolt head than normally seals the drilling in the head is often too deep for the banjo fitting on the feed line, which 'cocks' slightly and cannot seal. Bodge repair is double copper washers. True repair is to grind some of the rim away to clear the banjo neck.

 

John

[Guest ntc]

Ian,

Just a thought. Have you fitted an external oil feed to the cylinder head?

Is it this that is leaking, and seeping onto the rear of the head, as if between that and the block?

 

The recess drilled for the bolt head than normally seals the drilling in the head is often too deep for the banjo fitting on the feed line, which 'cocks' slightly and cannot seal. Bodge repair is double copper washers. True repair is to grind some of the rim away to clear the banjo neck.

 

John

 

Good tip that one John not a lot of people know that ?

[IanR]

Thanks for that John, but no I do not believe the external oil supply to the head is worth the risk. Kastner experimented, in the 60 's I guess, and found that oil pressure at higher revs (not to mention water pressure) is exceedingly low at the front of the block so taking any more from the main oil gallery is not I think going to help this. In addition, if you, rather foolhardily, run the engine with no rocker cover on, the amount of oil around does not give any impression that even more is required, plently of oil all over.

 

As a point of interest I thought I had nailed this problem a couple of weeks ago believing that the source of the leak was actually from the bolts that fix the rear engine lift eye. On investigation in a spare engine block I have I could see that its was just possible that the tapped hole in the block (supposed to be a blind hole) might just have broken through into the inside of the block. (slight variation in casting thickness for example) . I removed the eye, sealed the holes with some makeshift but oil tight washers and went for a run. When I came back, no oil so I thought problem solved, but I just had not gone far enough and the leak was still there.

 

It really is not much lets be honest its just as the thread says .. a bit annoying. I do not believe at present that doing nothing will lead to any disaster, but as always its not right and it should be.. I dont like things almost right!!

 

Many thanks