New engine rebuild running hot, Running Hot |
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New engine rebuild running hot, Running Hot |
57lincolnman |
May 27 2013, 12:39 PM
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#1
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Member Group: Members Posts: 174 Joined: 14-September 10 From: Los Angeles Member No.: 12,175 Region Association: Southern California |
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. |
avidfanjpl |
May 29 2013, 01:33 AM
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#2
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914 Hemophiliac Group: Members Posts: 720 Joined: 6-April 10 From: Bear, Delaware Member No.: 11,566 Region Association: MidAtlantic Region |
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 |
57lincolnman |
May 29 2013, 03:39 PM
Post
#3
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Member Group: Members Posts: 174 Joined: 14-September 10 From: Los Angeles Member No.: 12,175 Region Association: Southern California |
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 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. |
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