300 Degree Oil Temps!

[FJCamper]

Could the oil passages be too small or restrictive?

Gentlemen,

I'm preparing our Sebring race report, but first, we have to humble ourselves and ask for help and advice on an oil temp problem.

The problem is even with an oil pump (in which the cover plate and body match), a big 8-pass cooler in the Ghia's nose with a scoop to it, we still got 300 F. oil temp within minutes on the track.

Here's the specs. 32mm pump gears on a special in-out pump pumping first to an HP-1 filter and back.

A grooved oil piston, stock pressure relief valve spring.

24-foot round trip half-inch ID rubber oil line from an oil cooler adaptor to the 8-pass cooler in the bottom of the spare tire well.

A big air inlet slot for the cooler, and vent holes in the spare tire well behind the cooler to let the air out.

A scoop on the air inlet slot.

Now, we have a mechanical oil pressure gauge on the cooler inlet to measure oil delivery pressure to the cooler as well as the VDO electric pressure sensor to the VDO oil temp gague in the dash.

The VDO oil temp sensor is in the oil pressure relief valve.

***

Observed conditions.

1. Almost immediate oil pressure at both oil pressure pickup points. 80 PSI cold. Five minutes later, a drop to about 60 PSI as the oil pressure relief valve opens. Both gauges agree on the pressure.

2. Growing oil temps seem normal in rate/time, but with a laser-aimed pyrometer aimed at the oil pump face plate, 200 degrees comes up fast, even as the in-out oil lines to the filter show 10-to-20 degrees less.

3. Heads show normal operating temps. Plugs are burning tan, timing is spot on.

4. Pyrometer reads at pump cover and around oil pump cover are higher than anywhere else.

5. Oil cooler reads 300 F. with little difference in inlet and outlet lines.

I've never seen an oil pump as a big contributor to oil temp overheating. This is a strange one.

FJC

[ONEBADBUG]

Number 5. If there is no temperature drop across the cooler, then it isn't working.

[Slow 1200]

Number 5. If there is no temperature drop across the cooler, then it isn't working.

that, or oil is not flowing through it

[Dougwill002]

You did say BIG 8 pass cooler- I take it this means 8 tubes in total, I would say when dealing long duration high performance operation on aircool engines, we need to THINK BIG where cooling is concern something more like a oil radiator this is very efficient. I have read some of your other postings so i know your tuning is ok.

[buildabiggerboxer]

Could the oil passages be too small or restrictive?[/

24-foot round trip half-inch ID rubber oil line from an oil cooler adaptor to the 8-pass

FJC

Hi FJC, I don't understand what you mean by "oil cooler adaptor" is this a take off plate in the o/e cooler location in the fan housing?
If so, Why don't you feed the cooler directly from the pump outlet?

1/2 lines SHOULD provide enough volume for the job, That's all I use on dozens of cup car wet sump motors, but I always drill out and port those brass oil fittings, these are very restrictive, especially the 90* ones, tho you have pressure to die for, 150*C as you know is a killer, I suspect a volume problem, perhaps go up to 5/8" hose, and open up and port all the restrictive brass fittings, if that does nothing, the pump ports look as tho they may be restricting volume, some blue printing in there would help GPH I'm sure, look at the gear track marks by the outlet port, far too small a port, open that up to nearer the gear o/d and enlarge the outlet bore as large as possible, together with a drill out and port on those brass adapters, it can't make it worse whatever happens, best Regards BBB.

I've just had a look at the pump in component form, look how restrictive it is at the pump body
Port, the oil has to perform a 90* turn in the cover to feed that small bore in the pump body which must then align with the case port, I've not seen the pump in the flesh so can't tell how tight the cover 90* turn is, nor how well/ badly the pump body aligns with the case ports,
But that looks to be the weakness your looking for, time must be tight now to risk a development oil pump, I would suggest pulling an unknown and go back to a tried and tested setup, needs must in view, even go with an oil entry adapter at the control valve plug, i saw no
Problems with them ever, I saw blown of oil lines with jubilee clips, but it was on normal full flow cases, and loose clips most likely, but I recon the pumps flow volume is to low. BBB.

[Piledriver]

If hooked up off the oil cooler ports on the case:
If the pressure relief is opening the oil will take the path of least resistance, which will mostly be direct to mains.

The zero temp drop through the cooler is weird though.

The setrab/mesa style plate coolers are a lot more efficient.

Hook it up full flow, you are already plumbed.
Make a bypass adapter for the cooler boss.

[buildabiggerboxer]

That's it, returning oil through the oil cooler ports is meeting pressurised oil from the engine gallery's and fighting the 'other' oil feed from the pump pressure feed into the engine, so one supply is not flowing, and it's the oil cooler circuit, Which has lost some pressure over the pipe runs, so the bearing are living by the pump feed at higher pressure.

[Piledriver]

Yep, don't fall victim to faux flow cooling, you have the full flow going to the filter, finish the job.

That or slap in the CB drysump pump setup, 21mm pressure stage is enough for almost anything.

[Bruce.m]

The oil pressure relief valve (the surrogate for an oil thermostat), closes as the engine warms up. Not opens as the post suggests.

The relief valve opens when the pressure difference between the input side of the oil cooler circuit is higher than the output side by enough to close the spring. That's it.
If the pump flows too much and/or if the circuit is too restrictive the valve will open (perhaps partly) and the oil will not be cooled.

Jam the valve closed, fit an oil thermostat in the cooler lines (mocal or similar) & check the oil pressure in the oil return (if the cooler is clogged , for example, the pressure will be high at the pump but low at the bearings).

[Piledriver]

The main point is that if the relief piston is NOT ~fully up (highly UNlikely at high RPM w/big pump) the cooler gets little to no flow, and with the long lines, probably the latter.

The oil is only effectively forced 100% to the cooler when the piston is fully up (pressure controlled oil "thermostat" at work)

Big pump, add 20W-50, expect toasty oil temps at cruise, as the stock "thermostat" allows the pressure to set the temperature.
The oil temp will rise until the pressure drops enough for the piston to restrict flow to the mains and force oil through the cooler.
Its doing its job, as designed, but add thick oil and a huge pump... the poor piston spring combo don't know what the temp is, only pressure.
Seen it many, many times. Classic problem.

Full flow cooler (best with a real Tstat) is the proper (and long proven) solution.

[andy198712]

What are the sandwich Tstats like? That screw onto the filter head?
The 4 port local style looks restrictive also, being a 180 degree bend when shut??

Best of luck! Sounds like the answer is there though.

[Bruce.m]

Note.. The oil pressure relief valve cannot "measure" the actual oil pressure as it has no reference. It is moved by the difference in oil pressure each side of the cooler.

So, 60psi oil pressure pre cooler and 60 psi oil pressure after the cooler has no effect of the relief valve. However, if there is 45psi before the cooler and 30psi after the cooler, there is 15psi pushing the valve open.

[buildabiggerboxer]

Horses for courses again, road and track are worlds apart, stats are fine for a weekend warrior that's street driven, but not for racing, I've never used an oil stat or a water stat come to that for racing, bits left out cost nothing, weigh nothing and don't go wrong, complexity is the mother of unreliability, just look at the grief FJC has just now by introducing "a change", we all make rods for our own backs at some stage, usually by forgetting the KISS rule lol.

[buildabiggerboxer]

f there is 45psi before the cooler and 30psi after the cooler, there is 15psi pushing the valve open.

This is exactly what will be happening, there is always a pressure drop across a remote cooler installation, in FJC's install, with 20 odd feet of hose, it will be a considerable drop, one reason why racing D/S oil pumps have a large pressure stage.
The CSP and Bugpack oil return adapters work well for proper full flow remote cooler instals, the spring and piston is binned, the adapter fitted up and the o/e oil cooler ports need to be bridged.

[Piledriver]

Note.. The oil pressure relief valve cannot "measure" the actual oil pressure as it has no reference. It is moved by the difference in oil pressure each side of the cooler.

So, 60psi oil pressure pre cooler and 60 psi oil pressure after the cooler has no effect of the relief valve. However, if there is 45psi before the cooler and 30psi after the cooler, there is 15psi pushing the valve open.

Actually, its even simpler than that.

If the absolute oil pressure on top of the piston is enough to depress the piston/spring significantly, it opens a direct path to the mains.
Result: oil takes the ~8mm long path direct to mains, and there will be ~zero pressure differential across the cooler.
Piston is referenced only to the spring and the sump pressure via a return hole at the bottom.(which should probably be made larger than stock with a big pump)

At high rpm w/big pump, it's probably fully depressed and feeding back 70-80% of the oil to the sump.

With a conventional full flow setup, even that oil is cooled before being bypassed to sump.
Stock, it gets bypassed and not cooled.