2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Please help me find out why my motor just blew

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Old Aug 4, 2009 | 01:11 AM
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From: elmhurst ny
Unhappy Please help me find out why my motor just blew

ok so i just finished rebuilding the motor and everything is cool no leaks no oil burning nothing, the car idles fine absolutly nothing wrong with the car. so after it sits and idles for about 3-4 hours straight i take it out for a little drive just around my block and everything is cool until the motor starts dieing and slowing down so i through it neutral and the engine died, so i pop it in 2nd gear and try to turn on the car this way and the tires lock... i pull over and attempt to start the engine and nothing. i thought the battery was dead. so after charging it and boosting nothing. i thought the starter was bad. we tested it and it was fine... so we attempt to move the motor by hand and nothing, attempted to move it by ratchet and socket nothing... eventually we took out the front cover to see if the end play washers over expanded and seized the motor it wasn't it...but we noticed when we took out the front cooler lines no oil came out...same went for the rear one... AND THE OIL FILTER!! were assuming that its the oil control vavle was shut closed due to the fact that last year the motor went through severe overheating due to the blown water jacket and over expanded the valve shut... the oil metering pump lines were also dry. were assuming carbon lock up but the motor was brand new! eventually we get the flywheel moving and notice the motor had no compression AT ALL... so we spin the motor until we see the one piece apex seals and they were rounded out =(im here asking help diagnosing with what cause the oil to not circulate around the motor. can any one please help me? yeah i know i wrote alot but this was my first rebuild and it really sucks man so much time and effort put into the car... this will be soooo appreciated so i can be aware of what will cause these problem in the future and prevent them from happening. im just 18 years old and spent over $1300 on this rebuild. thanks again.
http://www.youtube.com/watch?v=iUMLQHOJPho
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Old Aug 4, 2009 | 05:08 AM
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One piece apex seals destroyed my last engine. I've heard nothing but bad things about them.

Other things... hmm... Idling it for hours won't do much. Break in is best done with varying RPMS, I.E driving it, but keeping it under redline for a few hundred miles. You didn't take it out and beat on it right after dropping in the engine did you?

I think its safe to say that your engine was starved of oil and locked up. What caused that is beyond my ability to determine though.
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Old Aug 4, 2009 | 06:12 AM
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I know it's not going to answer your question, but no oil pressure gauge when car was running?
Here’s some info:
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/new-rebuild-no-oil-pressure-853645/
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Old Aug 4, 2009 | 06:27 AM
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premix FTW, good insurance for lubing the seals
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Old Aug 4, 2009 | 07:22 AM
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was any attention paid to the oil pump? What about the oil pump chain and regulator?
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Old Aug 4, 2009 | 07:43 AM
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Also i noticed in the video that you had the turbo off the car, what did you do about the oil lines going into the turbo and out of the turbo? loop them together? block them off?

did you remember to install the oil pickup tube on the bottom of the motor?

That really sucks..
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Old Aug 4, 2009 | 07:44 AM
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Originally Posted by MazdalicousRx7
premix FTW, good insurance for lubing the seals
Premix wont combat full oil starvation.
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Old Aug 4, 2009 | 08:06 AM
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By the looks of the oil pressure gauge, it is pegged at the top, at idle. Seeing as I have poor oil pressure at idle (next to 0), I am not sure where the pressure should be, but I am assuming that it should not be at the top! Probably around the middle of the gauge at idle. Also, it could be possible your gauge is not reading properly, and you actually have 0 pressure. I beleive there is a thread around here, talking about the oil pressure wire being grounded, and pegging out at the top.

Pour some oil down the oil filter pedistal, and see if any comes out the oil cooler line. That will tell you if you are plugged between the pump and the filter (where the pressure is read from).
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Old Aug 4, 2009 | 08:26 AM
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Originally Posted by RRTEC
Premix wont combat full oil starvation.
actually it would of salvage most of the motor, since the the combustion chamber would always be lubed, you could have salvage alot of parts.
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Old Aug 4, 2009 | 08:57 AM
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well my guage in the car has always been crazy high and for the turbo oil lines just blocked them off. yeah were also thinking the motor starved and locked up =( but what would cause this? a defective oil pump? oil control valve being shut? clogged passage somewhere? were ripping the motor back apart sometime this week to understand exact what happened. i thought i would never see my rotors again after i rebuilt it. you know when you think you do everything right this happens.
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Old Aug 4, 2009 | 09:20 AM
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did you prime the oil system before you started the car?
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Old Aug 4, 2009 | 09:55 AM
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You may want to follow this thread as it's a little further ahead than you are. https://www.rx7club.com/2nd-generation-specific-1986-1992-17/swapped-oil-pumps-still-no-oil-pressure-854672/

Also, not trying to be a jerk, but if I just spent $1300 on rebuilding my motor, I'd make sure it was building oil pressure before I kept it running, much less take it for a test drive.

And 1 piece seals are good if your building a race motor. They can hold high amounts of boost great (30+ on meth/alch). For a DD motor, their not so great though.

Did you remember to put the little tooth back in for the oil pump when you were re-assembling the motor?
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Old Aug 4, 2009 | 12:34 PM
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im sorry to hear that happened, i know that feeling and its sucks hard. you learn from your mistakes and next time look over EVERYTHING first. best of luck to you.
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Old Aug 4, 2009 | 01:46 PM
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Originally Posted by MazdalicousRx7
actually it would of salvage most of the motor, since the the combustion chamber would always be lubed, you could have salvage alot of parts.
Prove anything you just wrote... I am interested to see any reputable sources that would say that premixing would save internal parts under the conditions of a full oil starvation issue.

I have personally lost motors to oil starvation and would have to say that if you have ever experienced an oil loss failure you would never write the premixing would help save engine parts.. Any traces of Premix oil would undoubtably burn up under the intense heat and friction caused by no oil lubing the moving parts.. Premix lubes the seals not the components.... Please do post up the amount of "oil" that would be injected per revolution during premix through the fuel spurts..
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Old Aug 4, 2009 | 02:22 PM
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the key in back of the bolt holding the oil pump in place? yeah its still there of course. im thinking its the oil control valve...can anyone prove to me that it could or couldn't be that? and how exactly does that valve work? when the motor is warmed up it opens? or stays shut? or regulates according to pressure and temp? sorry for all the noob questions but i never had this problem before and if i understand how it works maybe we can further diagnose this. =( thanks again
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Old Aug 4, 2009 | 03:10 PM
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that valve only blocks off the oil cooler during warm up. it has nothing to do with the rest of the motor not getting oil. should have primed the oil system before firing, but i'm sure you are going to do it next time.
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Old Aug 4, 2009 | 04:25 PM
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not priming the system would have just been some trivial premature initial wear, but it could have shown him there was a problem.

Still the motor ran for over 3 hours, I think if it ran for 3 hours even priming it would not have revealed the problem.
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Old Aug 4, 2009 | 04:56 PM
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not too sure but i think in blocking the oil lines going to the turbo stopped the flow to some crucial pieces causing the lock up
at idle the oil psi should be around 30 NOT 0 and NOT above 60
while driving the oil psi should be around 60
next time make sure that the engine is getting oil at the correct psi
should not run hot at all, and i dont think its good for the motor to run it open manifold
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Old Aug 4, 2009 | 06:15 PM
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^his oil pressure gauge is broken so he cant even tell how much oil pressure he has.
also blocking off his turbo oil line wouldnt have affected anything.
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Old Aug 4, 2009 | 07:01 PM
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great diagram... my money is on pickup.
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Old Aug 4, 2009 | 10:06 PM
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yeah i think RRTEC might be right... the pick up and maybe also the oil pump... guys ok so do any of you know how to improve the oil cooling system in these motors? i was thinking electric oil pump and removing all the valve that would ever close and cause something like this. pump to constantly move oil around the motor and open all the valves to let the oil run. i dont believe this will be bad for the motor. also im buying the OMP adapter to run 2 cycle oil in my motor. i have heard nothing but good things with this setup. any comments on my "oil system setup" that i have planned? thanks again guys this sucks so much that it happened but you learn from your mistakes and thanks again for the input.
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Old Aug 4, 2009 | 10:12 PM
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Everyone says the stock oil cooler is plenty sufficient, so I wouldnt be too worried about replacing that.

As far as electric oil pumps...dont quote me on this for certain but a co-worker of mine is into old mustangs, and I believe he had a high performance electric oil pump. It ended up blowing his motor because it pumped oil out of his pan so fast it starved his motor. Again, I'm not 100% if it was the oil pump, but I think it was.
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Old Aug 4, 2009 | 10:25 PM
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If he had no oil in the lines,I am betting that he didn't prime the oil pump so it would Suck up oil and circulate it..It can't Circulate oil with a big "hunk" of air in the pump..
the OP should have Filled the Oil pedestal up with oil,and also the Oil lines,.to make sure that the pump had enough of a Chance to get oil,.,But I think the best got to him and he wanted to Drive the car,,**** Happens..you pay in the end..Sorry man,
Oh ya..and get a friggin Oil gauge that works..That would have saved the engine right there..a measly 20 dollar aftermarket mechanical oil gauge.
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Old Aug 4, 2009 | 10:33 PM
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misterstyx69 your totally right bro. i didnt do that... i did not prime the oil pump and lines. i just dumped oil into the motor and turned it on. i really honest to god did not know i had to do all of that. trust me bro im getting like 50 gauges in my car now just be safe. im learning a lot from you guys uhm thanks again for the input. now i know...
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Old Aug 4, 2009 | 11:02 PM
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^^^And now i know cause i want to rebuild my motor when i get mine, geez hope you get it back together dude
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