Recently completed rebuild of 1.8L and it's running too hot. Oil temps climb to 230 with only about 10 minutes running. It doesn't matter how the engine is loaded. Items to consider: 1) case cleaned and checked for alignment; 2) LN pistons installed at 96mm with new Nickie cylinders; 3) cylinder heads (1.8L) cleaned and set for 8.25:1; 4) new connecting rods; 5) push rods check out OK; 6) car did not previously have thermostat or cooling flaps, so these were installed. Thermostat opens as it should at 180; 7) Air/fuel ratio is 12-14 and within spec; 8) engine timing within spec; 8) mild cam upgrade. 9) crankshaft and flywheel were balanced; 10) all engine tin is in place

Could it be that the engine cooling flaps are not working or reversed? All thoughts and commentary are welcome. This one has us baffled.

Are you actually driving it or is that sitting still?


Cooling flaps fail open...that should be easy to check.

Carb, or the original FI?

I have NEVER had any thermal control issues with a Nickies engine! That includes 280HP N/A T4 based engines running in Florida sumer heat.

You have something misconfigured, mis-tuned or some weird variable thats creating this issue.

Sensor and gauge match?

You list mild cam upgrade, and list "push rods check out ok"
Did you do the valve train geometry when you built the motor, or just use the stock push rods with the new cam? New lifters? Check bearing clearances?
Oil pressure ok?

Jeff

what weight engine oil? could be high oil pressure is bypassing the oil cooler.

The cooling flaps linkage can easily get over extended on install...
causing them to not function the way they were designed and not fail open...

I'd take a look at the flaps for sure

This is L-tronic 1.8L for 75. Sorry I meant to include that in the initial write-up.

10-12 psi at 3400rpm is the things nightmares are made of.. the norm should be 10psi for every 1000 rpm.

I vote the cooling flaps are stuck closed, not allowing any air over the oil cooler..

what oil are you using? It could also be a bearing with excessive clearance. Did you line up the dowel pins on the case with the holes in each bearing?

Thanks Jake. It is reassuring to know that the Nickies is a well engineered and highly regarded product. Could it be that I have a mismatch in the crankshaft and cam? The previous owner did a mild upgrade on the cam (WebCam) but I can't recall which one it is. He also modified the crankshaft for to 2.0 spec.

This was the same set-up that I had before the engine rebuild. At that time oil temps and pressure were reasonable (occasional high of 220) with oil pressure at high speeds in the 25-35 psi range. I have a calibrated oil temp gauge from a 911 that was part of gauge rebuild by Palo Alto Speedo. So, I think there's a match there between sensor and gauge.

Thanks for your response. We spent an entire day checking out the valve train geometry. We ended up using the stock push rods because everything checked out within spec. I will need to follow-up on the bearing clearances. That is a good point. Oil pressure is NOT OK. At 65-70 mph I'm getting 10-12 psi. Not good. Oil pressure comes on at idle when the engine is warmed up.

Good point. I need to check with engine builder as to what he is using. I know that it is a Brad Penn racing oil that he's using to break in the engine. I'll get back to you.

Good point. I need to check with engine builder as to what he is using. I know that it is a Brad Penn racing oil that he's using to break in the engine. I'll get back to you.

I will check with engine builder and get back to you. This seems plausible.

Time being, you can adjust your air flow meter to make things run richer. I had to do this when upgrading to a 1.9.

many believe they HAVE to run 50 wt. which all they are doing is creating heat and throwing away horsepower. you should taylor your oil weight to your psi and rpm. this is with full group 4 or group 5 (ester) synthetics. i think the bypass spring is set up for around 46 psi. racer chris or jake would know exactly. anyways when you are at high rpm, oil pressure is high esspecially with thicker oil. the engine goes into protection mode and bypasses the oil cooler to protect it. high pressure = resistance and heat. lower oil pressure = more flow. (too a point)

When there is too much pressure the relief valve opens, but it also closes. Shouldn't be open ever below 25 if working. For most cars once warm a single pause at idle will lower pressure enough to close the valve after warm up. Opening takes in the 40s because the area for oil to press against is smaller than the area after opening. I don't think this is overheating the car because the pressure is so low.

if you are seeing low oil pressure and high temperatures I would suspect an issue with the oil pump/relief system/cooler (rule the flaps out first) then continue on from there

Either low flow from the pump, low flow through the cooler or lack of cooling air seem to be most obvious

I doubt that it is a flaps issue. The pressure is so low that you could seriously harm something fast. I would not start it again until you have dropped it, taken out the pump, cooler and filter neck and seen if there is something wrong. Checking gaps sounds like you are already planning the motor drop. Sounds like a bomb ready to throw a rod or seize a piston. Air cooling problem with flaps only makes it hot. Not low pressure, if you are certain it is low, like 12lbs. That is less than 1 atmosphere. That cannot be good. My 911 gets to 55lbs. My 914's were always better than you are seeing.

I lost a motor at 3K rpm with about 10 seconds of low pressure and almost no time on the green oil idiot light being on. Burned a piston and fried the motor with bad oil flow and screwed timing. The piston caused the problem, but the failure of the circulation at the end roasted it good. I put it in neutral and when I stopped it, the motor never moved again until rebuilding. That was 1979 and it was on 30wt Kendall GT1 (Now owned by Brad Penn).

Be very careful until you are at least double the current claimed oil pressure, and even that is not so good. Install a HD oil pump after checking the cooler and oil filter assembly completely, and that means total removal. Cheap insurance on all 3 items is to check and replace.

You just spent way more on a motor. Nasty to spend it twice. Worse to lose the case and all that's in it.

I am working to be positive on the situation, but it scares me bad. The temperature is not the best indication of a problem in an aircooled motor. Oil pressure is god, temperature an irritating demigod.

John

Harve,
The problem has nothing to do with the cooling system.
If the oil is heating up that fast it isn't even going thru the cooler.
With such low oil pressure I believe the problem has to be in the primary oil circuit. Maybe the oil relief piston isn't seated in the bore and is allowing a high percentage of the oil back into the case before it sees the cooler or the bearings.

Even with the oil at 230F the pressure should be at least 25psi at 3000rpm.

If the bearing clearances were excessive the pressure would be low but the temp wouldn't go up so quickly.

What is the oil pressure when cold, at idle and at 3000rpm?
It should be in the range of 60-80psi.

its possible for a relief piston to stick in the bore if caulked a little bit...

perhaps you have full bypass if your piston is not seating at all...

in earlier post you mention mild cam, are you sure the cam is timed correctly. I have seen this in motorcycle engines with aftermarket cams timed as stock.

Though I suspect this isn't keeping oil pressure low I am curious about how those people with the aftermarket cams solved timing. What do you tune to if not the mark?
Thanks.

the timing sheet that is supplied with the cam, a degree wheel and dial gauge indicator. changing the duration and lift of the cam changes the cam timing.

This is a good point. The previous owner put in a Webcam #86 with a valve lift at .423/.423; duration 270 degrees; duration @ .050" 234 degrees. Will look at the timing based on the spec for this cam.

Thanks. Will check this out.

This was a test drive only. When I discovered what was happening, I shut the car down and it was towed back to the shop where the work is being done to avoid any damage. It will not be driven again until this issue is resolved. We did put an HD oil pump and replaced the stock oil cooler. I think we're going to have to tear the engine down again to determine if the main bearing clearances are correct and determine why the oil is not flowing properly to the oil cooler. The quick and easy check is to determine if the pressure relief valve is working properly. That would be an easy fix if this work the case. Will probably go back to a stock cam too.

Agreed, this is a nightmarish scenario. Hopefully, what is gained from this will be of benefit to the community here at this site. BTW, the mechanic is on his own dime now to resolve this issue.