• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

TR4/4A Oil oil everywhere

Share this page

The car has a lip seal on the rear main. The mechanic pulled the clutch while the gearbox was out and confirmed that there was no leakage there. The front seal was replaced about 12 months ago and there is no leakage there either. The engine has only done about 25k miles since I rebuilt it. It had brand new Mahle liners and pistons. It still could be a broken ring. We shall see.
 
Update. The pistons have been removed. The ring end gap is around .048" at the top of the cylinder and .025" at the bottom. As the recommended gap is .004" per inch of bore, it should be around .014". So I guess I now know why the crankcase is being pressurised! We have ordered a new set of County pistons and liners from Revington as Mahle seem to be very hard to get. Hopefully this will solve the problem.

The mechanic seems to think that petrol leaking into the cylinders has washed the oil off the walls and caused high wear. I am a little puzzled by that as we got 36mpg (imperial) on our long trips. I'm also puzzled as to how the petrol could drain from the tank, through the mechanical pump, up over the engine, into the carburettors and then into the engine. He has a very steep driveway and he got 15 litres of oil and petrol out of the sump when he drained it. I look forward to driving it again without leaving an oil trail!
 
Hi Barrie....glad to hear that your problem is nearing resolution...as a matter of interest are you planning to do the replacement with the engine in the car.
 
Foura said:
Update. The pistons have been removed. The ring end gap is around .048" at the top of the cylinder and .025" at the bottom. As the recommended gap is .004" per inch of bore, it should be around .014". So I guess I now know why the crankcase is being pressurised! We have ordered a new set of County pistons and liners from Revington as Mahle seem to be very hard to get. Hopefully this will solve the problem.

The mechanic seems to think that petrol leaking into the cylinders has washed the oil off the walls and caused high wear. I am a little puzzled by that as we got 36mpg (imperial) on our long trips. I'm also puzzled as to how the petrol could drain from the tank, through the mechanical pump, up over the engine, into the carburettors and then into the engine. He has a very steep driveway and he got 15 litres of oil and petrol out of the sump when he drained it. I look forward to driving it again without leaving an oil trail!
Click to expand...

Torn diaphragm in the fuel pump most likely...

Cheers
Tush
 
I skimmed back over all the posts in this topic, Rocky, so I may have missed it, but what carbs are on your 4a ?
 
malbaby said:
Hi Barrie....glad to hear that your problem is nearing resolution...as a matter of interest are you planning to do the replacement with the engine in the car.
Click to expand...
The engine is coming out Malcolm. I will go and help disassemble the interior so that we can take engine and gearbox out together. I agree with the mechanic that it is easier to do a good clean job with the engine on a bench.

I have had major problems with the new plastic transmission tunnel from Rimmers, with a very poor seal on the firewall end and the prop shaft hitting the tunnel at the back. I will re-use the old fibreglass one when I reassemble the car.
 
The car has SU HS6 carbs. They have had a couple of rebuilds and don't seem to be leaking at the moment, but if I wait a couple of weeks.........
 
malbaby said:
Were you intending to modify the camshaft and/or check the camshaft bearings while engine is removed.
Click to expand...

The cam was checked when the engine was worked on before the oil problem. Two worn lifters were replaced and the cam was reground to a 280 duration specification. It certainly had adequate performance on our trip. You could pull out to pass a semi-trailer in overdrive top and it would sail past, leaving the semi driver to clean the oil mist off his windscreen. The cam bearings were all renewed when I first rebuilt it. I put a Wade 113 cam in it then which had 25-65 timing. I don't know what the specs are on the new one but I presume that it is something like 27-73. The Wade was apparently not rotating the lifters so it wore grooves in a couple of them.
 
Latest update. The County liners were checked and found to be too high, so Geoff has sent the block off to be tanked, after which he is getting the block machined to get the liners to sit at the correct height. I queried why we could not machine the liners at the top, but he is adamant that it is the block that needs to be done. Any thoughts? My concern is that even at my advanced age, if I have to rebuild the engine again in the future and the next lot of liners are too short, I will have to shim them at the base.

Just out of interest, the only English thing in the County liners and pistons is the box. The liners are Indian, the pistons Chinese and the rings come from the good old U S of A. Ain't global trade wonderful!
 
I'm with you; only machine the block if it is wrong. If the liners are wrong, they should be machined or replaced.

Yeah, County has always been just a repackager. They buy whatever is cheap, put in their own box, and sell it.
 
I can appreciate why the mechanic would not want to machine the liners due to possible damage in the machining process.
How did the old to new liners compare in length?
I would be a little reticent in machining the block, thus reducing the deck height.
My suggestion is to seek expert advice before proceeding.
 
I was concerned enough to get a second opinion from another source who has a fine record in rebuilding TRs. He races his own 3A which puts out about 185hp. He has worked on my car before. He said that he would machine the block. Good enough for me.

I believe that the liners were about 20 thou proud which is rather a lot.

I'm looking forward to getting the car back. I won't be able to go to the World Triumph Day photo shoot tonight.
 
Back
Top