What would cause this?
- johnv
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What would cause this?
(that's oil ...) New build, on start up it obviously just pumped oil into the combustion chambers. It did start but it wasn't pleasant! I stripped the head and there's nothing obviously wrong with it
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Mk2 1968 Cooper 998 TPL555F
Mk1 1965 Cooper 1275 BFC110C
Moke out of boxes and built NDV100F
Mk1 1965 Cooper 1275 BFC110C
Moke out of boxes and built NDV100F
- timmy201
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Re: What would cause this?
Bad head gasket?
Oil getting through valve stems & seals?
Excess SU damper oil?
Oil getting through valve stems & seals?
Excess SU damper oil?
- johnv
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Re: What would cause this?
Not the dampers there was no oil in them
To have a pool of oil in all cylinders kind of excludes the others?

Mk2 1968 Cooper 998 TPL555F
Mk1 1965 Cooper 1275 BFC110C
Moke out of boxes and built NDV100F
Mk1 1965 Cooper 1275 BFC110C
Moke out of boxes and built NDV100F
- timmy201
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Re: What would cause this?
Do you have a PCV system or breather setup?
I remember my friend was particularly enthusiastic filling up the oil once and a lot went out the rocker cover breather
I remember my friend was particularly enthusiastic filling up the oil once and a lot went out the rocker cover breather
- johnv
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Re: What would cause this?
No .. there are breathers where the petrol pump would have been and on the transfer case but nothing connecting anything atm
No breather on the inlet manifold
No breather on the inlet manifold
Mk2 1968 Cooper 998 TPL555F
Mk1 1965 Cooper 1275 BFC110C
Moke out of boxes and built NDV100F
Mk1 1965 Cooper 1275 BFC110C
Moke out of boxes and built NDV100F
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Re: What would cause this?
Has the motor been freshly bored, new pistons and rings? Oil could be blowing past the rings from crankcase pressure.
- johnv
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Re: What would cause this?
Yes all of the above. Thoughts seem to be that the rings maybe upside down or the cam bearings are in wrong. Checked the one (cam bearing) at the timing chain end and it's fine (they were professionally installed so I suspect they're all fine) Pistons out next.
Edit : it wasn't fine it was installed the wrong way round
Last edited by johnv on Mon Apr 10, 2023 1:06 pm, edited 2 times in total.
Mk2 1968 Cooper 998 TPL555F
Mk1 1965 Cooper 1275 BFC110C
Moke out of boxes and built NDV100F
Mk1 1965 Cooper 1275 BFC110C
Moke out of boxes and built NDV100F
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Re: What would cause this?
Incorrectly specified guides/lack of oil seals can cause that. As can rings/bore/pistons.
Looking at the photo no 3 piston looks off in the bore. Did you check bore/piston/ring clearances?
Looking at the photo no 3 piston looks off in the bore. Did you check bore/piston/ring clearances?
- johnv
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Re: What would cause this?
All new oil seals (8) bores were machined to pistons
Mk2 1968 Cooper 998 TPL555F
Mk1 1965 Cooper 1275 BFC110C
Moke out of boxes and built NDV100F
Mk1 1965 Cooper 1275 BFC110C
Moke out of boxes and built NDV100F
- iain1967s
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Re: What would cause this?
How long did you run it for when it started? It can take a good few minutes for all the engine assembly lube and oil to get burned off.
Especially if you recently filled the oil above the top of the valve-guide seals quite a bit can leak down the stems while it’s taking time to trickle down the pushrod holes into the gearbox.
For the low price of a head gasket I would clean it up, put it back together, run it for the standard 15 minutes at 2500rpm break-in period, keep an eye on the temperature and oil pressure, and then see after that if there is still a problem.
While it’s running, take the oil filler cap off and look down with a flashlight. You should not be able to see a rising head of liquid oil - if you see it rising up above the valve step seals then 100% the front cam bearing is in backwards - ie slot vs hole location - and getting a continuous rather than a pulsed feed to the head.
Also if you have a compressor you could do a warm leak-down test, or just a regular compression test to see if the rings are sealing.
Especially if you recently filled the oil above the top of the valve-guide seals quite a bit can leak down the stems while it’s taking time to trickle down the pushrod holes into the gearbox.
For the low price of a head gasket I would clean it up, put it back together, run it for the standard 15 minutes at 2500rpm break-in period, keep an eye on the temperature and oil pressure, and then see after that if there is still a problem.
While it’s running, take the oil filler cap off and look down with a flashlight. You should not be able to see a rising head of liquid oil - if you see it rising up above the valve step seals then 100% the front cam bearing is in backwards - ie slot vs hole location - and getting a continuous rather than a pulsed feed to the head.
Also if you have a compressor you could do a warm leak-down test, or just a regular compression test to see if the rings are sealing.
- johnv
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Re: What would cause this?
I'm being told that this cam bearing is fitted the wrong way round causing oil to be pumped into the rocker cover
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Last edited by johnv on Sun Apr 09, 2023 4:47 pm, edited 1 time in total.
Mk2 1968 Cooper 998 TPL555F
Mk1 1965 Cooper 1275 BFC110C
Moke out of boxes and built NDV100F
Mk1 1965 Cooper 1275 BFC110C
Moke out of boxes and built NDV100F
- Exminiman
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Re: What would cause this?
There is another thread about this, it is a thing…sorry i couldn’t find it…
EDIT More by luck than judgement found this. http://mk1-forum.net/viewtopic.php?p=220076#p220076
- iain1967s
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Re: What would cause this?
That has definitely been pressed in backwards. The circular hole should point toward the water pump.
- johnv
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Re: What would cause this?
It was only run for less than .. I'd say 2 minutes total, most of it revving to see if the smoke would clear?
I'm going to take the block back to the machine shop and see what they say .. I built the engine in lockdown so a fair while ago, just decided to put it in TPL to see how it went. I found the receipt though!
I'll check that I've put the rings on correctly then put it back together.
I'm hoping the machine shop will put new cam bearings in (I'll check the orientation

Mk2 1968 Cooper 998 TPL555F
Mk1 1965 Cooper 1275 BFC110C
Moke out of boxes and built NDV100F
Mk1 1965 Cooper 1275 BFC110C
Moke out of boxes and built NDV100F
- Spider
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Re: What would cause this?
That's easily enough time to start glazing them, if that's what's occurred.
Noted the Cam Bearing, but your valve guides would need to be fairly warn and the valve stem seals not doing much to get this much oil in there.