Oil leak

Technical advice Q&A

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SimonBrown
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#1 Oil leak

Post by SimonBrown » Tue Jun 12, 2018 9:38 pm

My Series 2 OTS had the engine rebuilt about 2 years and 600 miles ago.
In normal running about there are no oil leaks. However on the two occasions I have done longer runs ( about 100 miles each, doing about 70 mph for most of the way) there has been considerable oil leakage from the rear main area, noticeable after the journeys. The oil pressure has always been high, at over 60 psi and only dropping to 50psi when thoroughly hot and ticking over. It has a lip seal conversion
When the MOT was recently renewed it was ticking over on the ramp for about 20 minutes and didn’t leak a drop.
Any ideas would be much appreciated
Thank you
Simon Brown
S2 OTS

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cactusman
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#2 Re: Oil leak

Post by cactusman » Wed Jun 13, 2018 5:15 am

Could be the pope that leads up to the cams. Check the banjo joint close to the water tap on the block. Could be a blockage in the crankcase breather meaning at high revs there is excess pressure in the crank case that is forcing oil past a seal somewhere...
Julian the E-type man
1962 FHC
1966 MGB....fab little car too

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SimonBrown
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#3 Re: Oil leak

Post by SimonBrown » Thu Jun 14, 2018 7:42 pm

Thanks Julian,
I have checked the cam feed pipe and this appears dry.
There appears no blockage in the breather as I can blow down the pipe and there is evidence of a rusty/ water stain in the air filter box, presumably from engine condensation.
I do agree though it does seem breather related as I would have thought the rear main seal would either leak all the time or not at all.
Appreciate your help
Simon
Simon Brown
S2 OTS

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christopher storey
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#4 Re: Oil leak

Post by christopher storey » Fri Jun 15, 2018 9:18 am

Simon : are you sure that the engine is not overfilled ? bent dipsticks often lead to this problem , as a search on this forum will reveal :sad: . Also, it is worth taking the breather "dome" off , not a big job, and seeing what is lurking behind there - there is a very fine mesh screen which can become blocked

Another source of leakage mimicking a main seal problem is seepage past the threads of the screws which secure the rear half moon(s) of the cam cover/head interface. I discovered that it was necessary to wrap the screws in PTFE tape to stop this on one of mine

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ALAN COCHRANE
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#5 Re: Oil leak

Post by ALAN COCHRANE » Fri Jun 15, 2018 1:54 pm

Simon

I have a similar problem with the cam oil feed pipe to the inlet side. It only seems to leak after a long run and I suspect that it’s due to the oil thinning out at full operating temperature. I don’t think you can achieve those conditions no matter how long you let the engine idle in the garage.
I’ve tried everything to stop it, including a combination of ptfe tape, fibre washers and using an oil stone to smooth the back of the cam housing. It has reduced but not stopped.
Christopher that a great idea about ptfe tape on the bolt threads. The two rearmost on my sump look exactly as you describe and until now I thought it was caused by the rear crank seal leaking.

Cheers

Alan
1962 S1 OTS-850389,1968 Triumph TR250, 1971 Triumph GT6 Mk3, 2008 Porsche Boxster RS60 Spyder

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JJC
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#6 Re: Oil leak

Post by JJC » Fri Jun 15, 2018 7:35 pm

Try running straight 30wt oil for a while...you will find the rear crank seal likes it, and might stop dripping altogether. Also, I am guessing you have an electric oil pressure gauge. Just a guess, as , except for race engines, street cars should show 10 lbs of pressure for every 1000 rpm's. If you are actually generating much more pressure then that, (hope not), that would explain the leaks. Good luck.

John

1973 OTS since new.

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mgcjag
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#7 Re: Oil leak

Post by mgcjag » Fri Jun 15, 2018 8:41 pm

Hi John...where are you getting these figures for oil pressure..and what engine are you refering to... Steve
Steve
1969 S2 2+2 & Building a C type replica

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Gfhug
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#8 Re: Oil leak

Post by Gfhug » Fri Jun 15, 2018 8:49 pm

As my S2 shows 60 psi at 2000-2500 rpm then according to jjc it is way too high

Geoff
S2 FHC Light Blue

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#9 Re: Oil leak

Post by JJC » Fri Jun 15, 2018 11:01 pm

General rule of thumb.......as old as time itself. High oil pressure at low rpm's means something is wrong....usually just an inaccurate gauge or sender. Test your system at idle with a mechanical gauge (warm oil) you will see what I mean..

John

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SimonBrown
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#10 Re: Oil leak

Post by SimonBrown » Sat Jun 16, 2018 8:18 am

I have been concerned about oil pressure as it is “ off the gauge” at much over tick over even when hot.
It never drops below 50psi even when thoroughly hot and ticking over at about 700 rpm
I have checked with a mechanical gauge which shows a max pressure of 70psi after a cold start.
This would appear to indicate the relief valve is operating correctly.
There doesn’t appear much consistency with oil pressure with these engines, but I am concerned it is too high?
Simon Brown
S2 OTS

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mgcjag
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#11 Re: Oil leak

Post by mgcjag » Sat Jun 16, 2018 8:39 am

Hi Simon....so you have tested with a mechanical guage and know that your problem isnt a faulty guage or sender so now you need to look at the filter head and filter....is it a standard type or is it a spin on conversion....high oil pressure points to a blockage somewhere so i would start with removing the filter head and checking it out.....some engine builder do use silicone for gaskets which can block passage ways so look for bits in the filter which may give an idea its been used... Steve
Steve
1969 S2 2+2 & Building a C type replica

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SimonBrown
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#12 Re: Oil leak

Post by SimonBrown » Sat Jun 16, 2018 8:59 am

Hi Steve,

It is the standard paper type.

I did look at you tube and there seem to be other Xke engines running around 60psi, yet others are 40

Thank you

Simon
Simon Brown
S2 OTS

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mgcjag
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#13 Re: Oil leak

Post by mgcjag » Sat Jun 16, 2018 9:38 am

Hi Simon....the Jag manual says 40psi at 3k rpm....you will see very different pressures on many Xks becaus nearly all use an electrical guage....the senders are notorious for giving incorrect readings and even fitting a new replacement can be hit and mis...... correct me if im wrong but from what you have said you have checked with a mechanical guage and seeing 50psi at 700rpm....this is very high... Steve
Steve
1969 S2 2+2 & Building a C type replica

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SimonBrown
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#14 Re: Oil leak

Post by SimonBrown » Sat Jun 16, 2018 12:50 pm

Hi Steve,
Yes I have checked with a mechanical gauge which I know is correct.
I am not sure what I can do about this, I am sure the relief video valve is operating correctly as the pressure doesn’t go over 70psi even when cold.
I am also unsure whether this alone would cause an oil leak in the rear main area after a long run at 60/70 mph?
Regards
Simon
Simon Brown
S2 OTS

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mgcjag
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#15 Re: Oil leak

Post by mgcjag » Sat Jun 16, 2018 2:44 pm

Hi Simon..sent you a PM..Steve
Steve
1969 S2 2+2 & Building a C type replica

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cactusman
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#16 Re: Oil leak

Post by cactusman » Sat Jun 16, 2018 4:59 pm

For what its worth I would agree with Steve. If you are getting up to 70 psi there is something wrong. My, admittedly well used engine gets to about 40 psi max at 3000 rpm and drops to about 15-20 max at idle.
Julian the E-type man
1962 FHC
1966 MGB....fab little car too

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SimonBrown
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#17 Re: Oil leak

Post by SimonBrown » Sat Jun 16, 2018 5:45 pm

I probably didn’t answer this correctly.
To confirm, with a mechanical gauge the oil pressure is: Cold 65 psi at 700 rpm tickover rising to 70psi at 2500rpm. Hot 50psi at 700rpm tickovertickover rising to 65 psi at 2500 rpm.
Regards
Simon Brown
S2 OTS

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#18 Re: Oil leak

Post by cactusman » Sat Jun 16, 2018 8:20 pm

Definitely high. I know it is stating the obvious but are you sure the pressure relief valve is not stuck shut?
Julian the E-type man
1962 FHC
1966 MGB....fab little car too

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#19 Re: Oil leak

Post by SimonBrown » Sat Jun 16, 2018 9:05 pm

Hi Julian,
Thank you,
I think I am going to have a close look at the filter housing and valves.
I did think that as the relief valve doesn’t open until 72psi ( I have read this somewhere), then it wouldn’t affect the oil pressure at less than this figure, but might be wrong.
Appreciate your help
Simon
Simon Brown
S2 OTS

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