So here is the scoop: Had a shop swap my son's great running 89 SOHC Auto for a 91 DOHC Manual. Everthing went in okay but...
The DOHC sucks big time... Compression is 90 91 93 152
Pulled the head and 234 cyl have sucked the vales up into the head. The motor started up and ran rough... I took it for a drive and it had no power... then it started running even worse...Took it back to the shop and messed around with it a bit...took the air box off and it seemed to run a little better for a few minutes. Then it just started choking, but still running...
At this point the shop pulls the head and says " $800 for a head rebuild" I poliltely said hang on one second while I pull your D#$! out of my A$$...
I just bought another motor that is compression tested at 182,183 185, 183 and that motor is going into the car next weekWhole motor cost $650...
What I want to know is what caused the first motor to crap out so I don't get a repeat performance...
The first motor had been sitting for about 14 months. Prior it had been running great and had just passed smog. per the seller... i beleive him cause i saw the smog cert.
the shop had a fair amount of trouble with the wiring harness swap. I am woundering if anyone has any ideas on what might have happened to cause these types of issues. Could it have anything to do with the wiring? How hard is it to swap the harness and hook up from 89 to 91?
Your thoughts are very much appreciated
SOHC TO DOHC... Didn't work
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Hijacker
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- Car: '92 240sx Convertible
'94 F-150 - Location: Fredericksburg, VA
that head had been screwed up previously. My friend's truck had compression tests of 160,120,110,165,170,105. And it ran like crap, I can't imagine running a car with 3 cylinders under 100.
I doubt it was the wiring. The SOHC harness and DOHC harness are quite different, but they can be made to work with each other very easily. All you really would need to do is swap the engine harness over with the ECU. Then it's a matter of swapping a few plugs around and you're done. it should be very similar to wiring an SR into a SOHC chassis, just without having to lengthen wires.
To me, it sounds like the shop is d!ck you around.
I doubt it was the wiring. The SOHC harness and DOHC harness are quite different, but they can be made to work with each other very easily. All you really would need to do is swap the engine harness over with the ECU. Then it's a matter of swapping a few plugs around and you're done. it should be very similar to wiring an SR into a SOHC chassis, just without having to lengthen wires.
To me, it sounds like the shop is d!ck you around.
Yeah I know I paid up for the replacement motor, but if it run strong and is really 185ish in all 4 cylinders then I don't really care about the cost.
As for swapping the harnesses... The shop is really struggling with this... they don't have the tach or the temp and oil sensors working. They are taking hours and talking about needing to "splice" a bunch of wires and cut the harness I paid 100 bucks for.
Is there some place I can send these guys to really specific instructions on completing the wiring without cutting?
Do you guys think the motor sitting for a year could have caused such a lack of lubrication that the motor was damaged before the oil pump got oil to all the moving parts?
As for swapping the harnesses... The shop is really struggling with this... they don't have the tach or the temp and oil sensors working. They are taking hours and talking about needing to "splice" a bunch of wires and cut the harness I paid 100 bucks for.
Is there some place I can send these guys to really specific instructions on completing the wiring without cutting?
Do you guys think the motor sitting for a year could have caused such a lack of lubrication that the motor was damaged before the oil pump got oil to all the moving parts?
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Hijacker
- Posts: 14373
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- Car: '92 240sx Convertible
'94 F-150 - Location: Fredericksburg, VA
The tach is simple. Get a DOHC tach. It reads a slightly lower voltage than the SOHC tach, but you can just bolt a DOHC one right in and it works. Simple.
I'm surprised they don't have any wiring diagrams if they're wiring a car. It's almost idiotic to try and hardware a motor into a car without some sort of electircal diagram.
As far as getting the oil and temp senders working, I'd have to sit down with a SOHC and DOHC wiring diagram to find out what the difference is. I have a DOHC KA wiring diagram, but I unfortunately, do not have a SOHC KA diagram, so I can't compare and guide you on that.
The motor sitting around wasn't the problem. We import motors taht were witting in japanese junk yards for years and they fire right up. When you change the oil, you pour it into the head, so it would have lubed up all the head parts before it made it's way back into the sump. I think that motor was a bit screwed before it was sold to you. In the future, I would ask for pictures of the guy taking comp readings from all the cylinders, and if possible to see a leakdown figure as well. I wouldn't rely on a motor because I saw a smog chart. Anyways, you have a new motor that has good compression, so I wouldn't worry too much about it now.
I'll see if I can't finagle a SOHC wiring chart from my friend when he gets back on Tuesday. I've been meaning to steal a diagram from him anyways to complete my FSM collection on my computer.
I'm surprised they don't have any wiring diagrams if they're wiring a car. It's almost idiotic to try and hardware a motor into a car without some sort of electircal diagram.
As far as getting the oil and temp senders working, I'd have to sit down with a SOHC and DOHC wiring diagram to find out what the difference is. I have a DOHC KA wiring diagram, but I unfortunately, do not have a SOHC KA diagram, so I can't compare and guide you on that.
The motor sitting around wasn't the problem. We import motors taht were witting in japanese junk yards for years and they fire right up. When you change the oil, you pour it into the head, so it would have lubed up all the head parts before it made it's way back into the sump. I think that motor was a bit screwed before it was sold to you. In the future, I would ask for pictures of the guy taking comp readings from all the cylinders, and if possible to see a leakdown figure as well. I wouldn't rely on a motor because I saw a smog chart. Anyways, you have a new motor that has good compression, so I wouldn't worry too much about it now.
I'll see if I can't finagle a SOHC wiring chart from my friend when he gets back on Tuesday. I've been meaning to steal a diagram from him anyways to complete my FSM collection on my computer.
the wiring is very very simple. the entire engine harness and ecu swap directly, just unplug the SOHC and plug in the DOHC. the DOHC tach needs to be swapped into the SOHC cluster.
My water temp gauge doesnt work either, i just never bothered to fix it (i have an autometer).
the last bit of wiring is the only semi-not-straight-forward part. at the ECU, there is a small harness, like 13 wires, the goes from the ecu up into the dash. this harness needs to be spliced. take the original and the new one, cut them both in half. use the SOHC side for the part that goes into the dash, and the DOHC side for the plug near the ecu. match the colors up, and connect. not all the wires will match up, only like 7, thats all you need. leave the rest alone.
done.
My water temp gauge doesnt work either, i just never bothered to fix it (i have an autometer).
the last bit of wiring is the only semi-not-straight-forward part. at the ECU, there is a small harness, like 13 wires, the goes from the ecu up into the dash. this harness needs to be spliced. take the original and the new one, cut them both in half. use the SOHC side for the part that goes into the dash, and the DOHC side for the plug near the ecu. match the colors up, and connect. not all the wires will match up, only like 7, thats all you need. leave the rest alone.
done.
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_/_/_/M aurice
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The only things you should need for a E to DE swap is the DE harness, ECU, and a complete motorset (random stuff including distributor, and DE tach.)
You can use the SOHC transmission no problem.
Hit me up on MSN - [email protected] if you have any questions about the SOHC to DOHC swap.
I think I'll start writing up a FAQ about it, everyone seems to have problems with it.
You can use the SOHC transmission no problem.
Hit me up on MSN - [email protected] if you have any questions about the SOHC to DOHC swap.
I think I'll start writing up a FAQ about it, everyone seems to have problems with it.