Oil flow to cooler - strange problem

[gavinlit]

I seem to have a problem with oil flow to the front cooler on a 77 c3. History - car was running too rich, timing adjusted, dizzy serviced (previously not getting full advance). Timing and a/f mixture now seem to be at appropriate levels. There appears to be a lack of flow to the front oil cooler but the thermostat has been checked (and swapped), and the oil lines blown/cleaned out. So there's no obstruction, the thermo seems fine but there's barely any oil getting through when the engine heats up (talking about midway on the dash gauge). I've read lots of previous threads but can't find reference to a similar oil flow problem. Any ideas?

Some 25k ago a new thermostat was installed due to the car running too hot & this seemed to fix the problem right away.

Secondary question - would a car running overly rich mask an overheating problem? I ask this as the overheating issue seems to only have arisen after the a/f mixture has been adjusted. This in itself doesn't explain the lack of flow to the front cooler but it's interesting that I didn't previously notice overheating when the car was running rich.

[ossiblue]

The external thermostat should be opening at approx. 180 degrees F. If your car is showing temps at the mid-gauge range, and the gauge is accurate, then the thermostat should be completely open and the line to the front cooler should be hot and the return line a bit cooler. When you say barely any oil is flowing I am assuming you mean the temps of the lines has remained cool. Given you've cleared out the lines and cooler, I'd suspect a stuck external thermostat--you may have to remove it and inspect/test/replace the plunger. This is based on the fact that your gauge is accurate and the temps are truly as high as indicated.

It is also possible that an overly rich mixture will make your engine run cooler, but I can't say as to how much and if that would account for the temp changes. Conversely, incorrect timing can make the engine run hotter and you did mention changes in the distributor/timing of the car.

Regardless, the oil cooler system doesn't seem to be performing correctly--the lines should be hot at the temps indicated.

[gavinlit]

Thanks LJ - all good points. The external thermo has been checked and swapped out for another for testing - yet the oil flow is still pretty much nil.
Certainly incorrect timing could make a car run hot but the timing seems to be spot on at the moment.

[fintstone]

Make sure one of your lines have not been crushed. If not, and the lines on the other side are not getting hot...when the engine is over 180 degrees F, it is the thermostat. Replace the regulator piston on the thermostat 930-107-155-00-M322.. You can order it from Pelican.

[gavinlit]

And that's the problem fint, the thermo has been tested, swapped & it seems to make no difference. So I'm left wondering if there are any other possible culprits. I'll check the lines again - tyres have recently been fitted so who knows.