Flywheel oil leak, high oil pressure and burning oil

rlepecha · Jul 12, 2015

Trikky2 said:
Hmm. Puzzling one this. After 400 miles the engine temp should have dropped by now.

Have you checked the ignition advances to a max of 28 to 32 at around 3000 rpm without the vac advance connected?

Reason I ask is because if the advance is sticking it could cause it to run hot plus some of the aftermarket ones have been known to under advance - particularly the 009 copies.

I know its puzzling! It puzzled me with my last engine and now this one too..

Timing is set to 28-30 degrees total advance vac disconnected. It's set in lower portion in an attempt to reduce the temperature, although it have tried less and more advance.
It's got an SVDA fitted, I unhooked the vacuum and plugged the line earlier thinking it could be excessive advance but it made no difference.

Dwell set to about 50 degrees, don't think that makes much difference though.

I have tuned the carbs using a CO Meter, I know they run very slightly lean while on partial throttle/idle jets but haven't got round to switching the jets. Above 3000 rpm it is fully on the mains and reads about 3.5% CO, so fairly efficient and correct burning.

I tried most things with my old engine which did the same thing, I presumed it was due to the old oil cooler so replaced it on the new engine. I don't know what else to try, hence the external cooler!

Edit - just to add, I replaced all the engine bay seals with the new engine too. Checked around the tinware for any obvious gaps, no gaps.

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Trikky2 · Jul 12, 2015

I agree with you. In your situation I would try a slightly richer mixture too.

Its so strange you had the same problem on the previous engine. Hence why I asked about how accurate the gauge was.

Were the current carbs fitted to the previous engine too? If they were then it might be the link your looking for.

How are you measuring the mixture when the engine is under load? Was this done on a rolling road?

Trikky2 · Jul 12, 2015

Another thought. When you changed the barrels and pistons did you change the heads? If not - did you check valve guide wear?

Worn guides will cause hot running because the valve will not seat correctly and hence will not be able to dissipate its heat via the valve seat into the cylinder head. It will then overheat and can cause pre ignition at higher rpms while under load.

rlepecha · Jul 13, 2015

Thanks for the reply.
The heads on the new engine are a different set.
Valve guides seemed in good condition, the valves had very little play in the guides.

I haven't had the mixture set under load, that is one thing I am also yet to do. According to the recommend jet sizes for a 1600 with Webers, most people use a 140 main and I fitted a 150 main to be 'on the safe side'.

The only other thing that has crossed my mind, could my temperature sender be directly below where the oil drains back from the barrels/piston walls and therefore be reading a localised hot spot. The sender is a thermocouple fitted inside a tube the correct size for the dipstick tube which is slightly below the 2nd barrel.

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Trikky2 · Jul 13, 2015

I would think if the sender is immersed in the oil, the reading should be right but its easy enough to check out your idea by using one of thos IR thermometers, taking a reading off say the drain plate.

This would also double check the gauge - in case it was reading ok when you tested it at 12v but actually reads higher when the engine is running at 13.5v.

rlepecha · Jul 14, 2015

Trikky2 said:
I would think if the sender is immersed in the oil, the reading should be right but its easy enough to check out your idea by using one of thos IR thermometers, taking a reading off say the drain plate.

This would also double check the gauge - in case it was reading ok when you tested it at 12v but actually reads higher when the engine is running at 13.5v.

Tested sender with IR thermometer in boiling water(or near boiling), compared results between the IR and Sender, results are within +/-5c which I think is acceptable based on the in-accuracy of the IR due to the emissivity of the materials. (These tests were done with the engine running, so sender at 13v+)

I also took the bus for a long run to get the oil plenty warm, I got the oil up to 99-100c per the sender then checked the temperature with the IR in multiple places.. Sump plate, oil cooler, oil filter, oil hoses, case etc, all results read an average of about 15c less than the sender..
Appears the sender must be sat in a location where the oil has a localised hot spot, I have moved the tip of the sender so its not so deep into the oil/sump with no change.

I am going to order some fittings etc to install a gauge into the oil hoses to confirm these results.

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