Front Oil Cooler

[HawgRyder]

My front oil cooler is bypassed with a U-shaped hose.....that has a kink in it.
I klnow that this will effectively stop flow through the hose.
Question....when the thermostat opens...does all the oil pass through the front cooler?
In other words...am I oil starving the engine?
The pressure guage stays up..but I'm not sure I'm looking at the actual pressure being fed to the bearings.
Many thanks...Bob

[Chuck Moreland]

Your engine is safe, but you need to fix the problem.

Your engine has what amounts to two oil pumps. The first is a scavenging pump that pulls oil out of the sump and routes it through the external oil cooler, filter and into the tank. The second draws oil from the tank and pushes it through the internal oil cooler and internal oil galleries to lubricate the engine. It is this second section that your pressure guage reads.

Your external thermostat has a bypass valve that allows oil to pass in the event the cooler is clogged (as your is). This prevents oil starvation.

You need to fix that problem for a couple reasons. Firstly you aren't getting the cooling your engine is designed to have. Secondly your scavenge side oil pump is straining extra hard to push open that bypass valve. This will reduce the life of the pump.

[HawgRyder]

Thanks Chuck.....your explanation may also explain an oil leak that has occured.
I though it was from the oil cooler...but now I'm thinking it may be from some place else close by.
So...if the front oil cooler is on the return side of the pump...and the thermostat is between the pump and the tank....how much back pressure does the closed valve in the thermostat put on the return?
Or does that vary from car to car?
Bob

[J P Stein]

Not all external thermostats have a presure relief.
Fortunately, Porsche's have the feature....on the aftermarket side of the house, Troutman's have it. TTBOMK, that's the onliest one that does.

As for how much pressure can the scavange side of the pump develop: I was told by a west coast racer, that he had seen 165 psi on gauge rigged to the scavenge side......cold oil and long lines......the question arose after I blew an aux cooler.....I don't think he was foolin'.