Vilhuer

Can't find anything with current seach functionality.

I know there has been some talk long time ago about oil bypass valve. The one which was deleted from engine block around '88 MY IIRR. Its purpose was to open up at 0.5-1.0 bar pressure difference to protect inside radiator oil cooler.

Why was it deleted?

Does it make any difference that later MY cars have separate cooler under radiator?

What needs to be done to delete it from older engine block? I recall seeing some factory document about parts needed for delete but can't find any info.

SharkSkin

I was looking at the oil circuits a few days back, 1988 MY changes doc IIRC and it seemed that the oil cooler normally saw up to 8 bar on both ports while cold(no flow) then when hot all oil flowed through the cooler, at up to 8 bar. Or whatever pressure the pump is putting out, until it exceeds the main bypass pressure of 8 bar.

dprantl

I thought the bypass was removed when they moved the oil cooler out of the radiator and made it external?

Dan
'91 928GT S/C 475hp/460lb.ft

Tom. M

There are two bypasses on the 87/88/89 S4 blocks if my memory serves me correctly (not sure if this applies to the 85/86 blocks..but would assume so). Up to 89 there was one bypass for the "oil pump overpressure" that would dump directly into the pan if it exceeded a certain pressure, and one for the internal oil cooler to keep the oil from over pressurizing the the radiator oil cooler.

After 89 they went to the external oil cooler and the one pressure relief bypass (for the oil cooler) was removed since I guess Porsche figured you would be able to see if the oil cooler blew...

I've replace spring/plunger in the track car engine (91 block)..pain in the butt...and I'm running an oil cooler radiator..Hmm..am I asking for trouble????

I guess I don't see the need to remove the oil cooler bypass....if you have internal or external..it will still behave properly.however, in my case, having internal oil cooler with no bypass could concievably be an issue....

James Bailey

You could replace the spring with a solid sleeve that would hold the piston closed all the time. That assure that all the oil would pass through the cooler once the temp is high enough. The internal restrictions of the air to oil oil cooler (it is much larger) might have been enough to cause the bypass to bypass all the time ???

Hilton

Try this

"oil" and "bypass" and "delete"

(you need to include the quotation marks - they've screwed up string handling)

James Bailey

Probably could just shim the spring to make it take more pressure to bypass...that would be the simplest.

Fabio421

advanced search still works

Vilhuer

That helped a lot but I still can't find actual thread which had factory document containing more info. Jim's idea of making spring stronger might be best option if nothing new comes up. '88 and '89 MY yearly changes documents were first ones I looked. Nothing there or anywhere else I have managed to find.