oil leak.

[rudi]

Even with a new cranck seal (conversion) my engine is leaking oil. (found n the bellhousing as before). The engine has the conversion since long. I am 99% sure the oil is leaking passing the oil seal. The enigine is not leaking when running at thick over during 20 min in the garage. Only after and during a trip the oil starts coming out.

I have a small breather pipe in the alu rocker cover and have a ventilation where the fuel pump has been mounted (now electronic). I am looking for the cause of the leak.

Another issue I have is a vey high off the scale oil pressure at high engine revs. even when hot. Loosening the PRV valve does not solve the "problem". Pressure at hot thickover is slightly above 2 so quite ok. The pressure follows the enigine revs going from 2 to off the scale.

Thinking over all this and looking for some logiic, I came up with foll. concl. : When there is a high pressure in the cranck case, caused by eg. blow by, (more blow by at increased revs) that the build up pressure in the cranck case gives a "back pressure" to the oil causing a (too) high oil pressure at high revs. I guess this could make sense and would than also explain the leaking rear oil gasket (not the high oil pressure is the cause but the cranck case pressure).

So cranckase pressure is the only cause I can think off. If this would also explain the high oil pressure (at higher revs) than this is a 2nd reason to look for a blow by problem.

Will a simple compression test show signs of blow by, or how can I (let) test this to be sure?

Thanks for any comment you might have,

Rudi

[Don Elliott]

Rudi - Do you have the inverted crankcase vent pipe attached to the block just to the rear of where your mechanical fuel pump used to be ? This should allow all the pressure out. Unless it is blocked ?

[rudi]

Hi Don. No the original vent pipe like in the TR2-4 engine is not there. (THe block is from a TR4A). I have a blanking plate on the hole where the fuel pump used to be. This plate has a vent pipe with a diam of approx. 1,2 to 1q 1.5 cm and goes up to a catch tank sitting next to the battery. Both vent pipes (2nd one from the rocker cover diam 1 cm) blow air when the engine is running

I intend to fit the old rocker cover with the original "open" oil cap, again and see if this helps.

Rudi

[marvmul]

Rudi,

I would favour another possibility. There is no reason why your engine should make such high oil pressure. Probably the gauge is not accurate anymore, just like on a lot of other sidescreen TR's.

If the oil pressure is rising with rising rpm, maybe the pressure at idle and low rpm is rahter low.

 

If the clearance of the main bearings and especially the big end bearings are too wide, an awful lot of oil will escape at high rpm via these bearings into the crankcase and the oilseal, even a conversion, can't handle it anymore, hence the leak.

It's only a supposition, to know it for sure, one could use PLASTIGAUGE (PLASTIGAGE in some countries) : this consists of small plastic filaments. After removing the bearing caps, a couple of filaments,cut at length, are placed between cap (shell bearing) and journal, the cap bolts are torqued with the recommended force, and the width of the squeezed filaments will tell you the clearance of the bearings (normally about 0.05mm).

If the clearance is wider, worn shell's or not carefully grounded journals can be the cause : a wider clearance, if not too exagerated, will do not much harm. It's up to you then if you can live with the oil leak.