Blowing oil in Shetland

[qkingston]

Members of the Clyde Valley Group have just returned from an epic tour of Shetland (for the Classic car Show), Orkney and NE Scotland; fantastic drive, great roads and lovely people. Anyway the point of the post is that during the trip I noticed that my 4a was spraying oil out of the exhaust (wet oil spray, not oil smoke), a bit embarrassing on the ferries as the car behind got a little front grille lubrication! This was definitely getting more noticeable towards the end of the trip, as was the consumption of oil. Our local discussion on the cause suggested that it might be oil getting down one or more exhaust valve stems/guides/seals and being sucked out down the exhaust rather than being burnt in the combustion process. Any thoughts on this and has anyone experienced it before? Also, I'm anticipating taking the head off to investigate/repair; where would be best to go for decent valves/springs/guides/seals?? TR Shop??

Your thoughts much appreciated

David

 

[RogerH]

Well done David on your tour of the Northern Isles. I love Shetland.

I use to work there in ther 70's on the Helicopters and have done 2 mini tours of both Shetland and Orkney.

As for you oil.   Is your breather system working. If not then the crankcase could pressurise and feed back down the Exhaust valve stems.

Also do not over fill your sump oil level keep it below 1/2 way on the stick.

 

Roger

 

 

 

[Dale Moore]

Sounds a bit extreme for enough oil to get past the valve stems to produce actual liquid oil in the exhaust. Does the engine run ok otherwise ?  I would do a compression test first to rule out a damaged piston.

Dale

[trry]

If it were just valve guides, I'd expect blue smoke rather than oil spraying from the exhaust.

Before pulling the head, a compression or leak-down test might be worthwhile. Worn rings can create enough crankcase pressure to push oil through the engine on a long run.

Could save a lot of guesswork before buying parts.

Terry

[Hamish]

It’s not just wet soot blown out the exhaust  is it ?

which could be head gasket introducing the water into a sooty exhaust. ?

doesn’t explain the oil use tho.

[Dale Moore]

I had exactly that Hamish. Watery soot being blown from the exhaust. Water level falling but no pressurisation in the cooling system. After pulling the head I found a crack between the water jacket and one of the exhaust ports !

Dale

[qkingston]

Thanks for the suggestions. I will definitely do a compression check before anything else

David

[Hamish]

Might need to do a leak down test too just to make sure. 

[qkingston]

Roger that

[Z320]

On 6/13/2026 at 4:56 PM, Hamish said:

It’s not just wet soot blown out the exhaust  is it ?

which could be head gasket introducing the water into a sooty exhaust. ?

doesn’t explain the oil use tho.

I had wet soot blown out on my TR4A when I started the engine,

and to avoid this on the tiled garage floor a cardboard laying there behind the car.

When the engine and exhaust are cold the steamed H2O from the fireing process condenses there to liquide water.

It is much reduced since I reduced the soot by fitting valve stem seals from Elring, produces for a VW truck (with Toyota engine).

This also reduced the oil consumption.

When I fitted the seals (with the head in position) I noticed there have been rubber seal before,

but they have not been tight on valve guides and stems.

Ciao, Marco

Edited June 15 by Z320
Stems, not valves

[Z320]

 

[qkingston]

Thanks Marco, I had heard about those stem seals, they sound like a good idea. I will do the compression test and leak down test and see what that indicates

Regards

David

[Z320]

1 hour ago, qkingston said:

Thanks Marco, I had heard about those stem seals, they sound like a good idea. I will do the compression test and leak down test and see what that indicates

Regards

David

A lovely idea to let the head in position and do further tests!

[Pontious]

Out of interest, what psi would be regarded as a good result in a compression test?

Presumably you would do one test dry and a second test with some light oil in the cylinders?. 
 

David

[RogerH]

57 minutes ago, Pontious said:

Out of interest, what psi would be regarded as a good result in a compression test?

Presumably you would do one test dry and a second test with some light oil in the cylinders?. 
 

David

Hi David,
The first important thing is to have all four pots giving a similar reading (usually within 5psi).
Then pressure reading - this could be anywhere between 140 to 180 psi.

If you get a big variation then use the oil and this may pin point what is not right.

Do it with the throttle wide open 

Roger

[Pontious]

Thanks Roger. That’s v helpful. 
 

David

[qkingston]

OK so the results are in:

Compression test:

#1 189psi, #2 184psi, #3 190psi, #4 190psi

Spark plug tips all lok ok? base a little sooty??

Rocker cover off, plenty of oil, no mayonnaise

Dont have the kit to do a leak down test yet, but working on it.

Any thoughts?

[Chilliman]

Nothing wrong with those figures, still looks like valve guides to me. I started off the season chucking clouds of oily smoke out the exhaust & fitted a set of guide seals and all good ever since.

[qkingston]

Thanks John, I think its pointing that way

Regards

David

[harrytr5]

I fitted a tr2-3-4 snorkel  to a mates TR4 and it enabled the bottom end to breath and stopped the oil pissing out everywhere. That could be a cheap fix. I had to drill a 3-4" hole in the triangle support plate which is in front of it and it gives you a view to pull out the capping and then insert the snorkel in its place. Worth a try and worked for him.

Regards Harry

[qkingston]

Harry, that's interesting. I have the 4a PCV fitted which is supposed to breathe the top and bottom ends. I also bought a snorkel of Rich C-R but never fitted it as I was persuaded that it didn't need it... Maybe I should?

David

[Z320]

My recommentation is to keep the PCV valve but check it for propper working.

Don‘t make your 4A with the snorkel older than it is.

Ciao, Marco

Edited June 21 by Z320

[qkingston]

Thanks Marco, I've always read your advice and explanation of the PCV, and I believe it is set up correctly. However, when was checking it I noticed that the new metal disc on the top of the PCV had a piece of plastic partly stuck on the underside, it is possible that this plastic was converting the small breather hole in the disc. Could that cause over pressurisation in the engine? 

[Z320]

Hmmm, from my memory……

due to the workshop manual the membran must be checked and cleaned every ? miles (the top side).

If the membran glues on the top cover the valve remains open and does not reduce the inlet vacuum.

I don’t know what happens in this case, checking the membran from time to time I never had the need to clean it.

Ciao, Marco

[rcreweread]

10 hours ago, qkingston said:

Thanks Marco, I've always read your advice and explanation of the PCV, and I believe it is set up correctly. However, when was checking it I noticed that the new metal disc on the top of the PCV had a piece of plastic partly stuck on the underside, it is possible that this plastic was converting the small breather hole in the disc. Could that cause over pressurisation in the engine? 

David - there should be a rubber diaphragm under the top cover which sits on top of the metal disc beneath it with it's spigot facing down into the spring below it - I wonder if the diaphragm has been replaced with a piece of plastic - this could be part of your problem

Cheers Rich