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Old 01-14-2010, 07:27 PM   #1
bradenman1
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Default 1990 supra turbo partial rebuild. Please Help!!!

I just got a 1990 supra turbo. It has a few problems that I need help with

1. The valve cover gasket is leaking oil I saw that all the valve cover bolts are philips head?? I would think that this would cause alot of leaks due to the fact that you can't torque them like a hex head. I would like to know if there is any replacement bolts I could get to fix this leaking problem.

2. Ok the turbo boosts still to about 5 or 6 psi (is that normal boost or should it be higher?) but it seems to only be within 3000 and 4500 rpms or so, once it pases this point it doesn't seem to pull verry hard. It does have 237k miles on the car and the turbo was never rebuilt. And theirs also an exhaust manifold gasket that is blown and I'm almost positive that the cats and exhaust system is cloged. Would this cause the slugishness to happen?


I'm sure there's more I just can't think right now. Please help. Thanks : )

Sorry if there are typos I'm using a phone

Last edited by bradenman1; 02-11-2010 at 06:12 PM.
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Old 01-14-2010, 07:39 PM   #2
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Replace the valve cover gaskets first. They're probably stock in which case they've most likely compressed over the years.

You may replace the screws with M6 bolts. The philips head screws were used in order to prevent over tightening and make it easier to service. The torque spec is only 22 INCH lbs. Do not over torque them or they will leak again. Also don't forget to put a small dot of RTV in the corner where the #1 cam cap rises up from the head.


Yes, an exhaust leak before the turbo can cause low boot. Another possibility is a weak spring in the actuator. As far as I know you cannot get a replacement actuator... you can add an aftermarket universal if yu fabricate a custom bracket or you could add a boost controller (a manual boost controller can be built very cheap!). Get the exhaust leak under control first.
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Old 01-14-2010, 08:10 PM   #3
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Quote:
Originally Posted by cre View Post
Replace the valve cover gaskets first. They're probably stock in which case they've most likely compressed over the years.

You may replace the screws with M6 bolts. The philips head screws were used in order to prevent over tightening and make it easier to service. The torque spec is only 22 INCH lbs. Do not over torque them or they will leak again. Also don't forget to put a small dot of RTV in the corner where the #1 cam cap rises up from the head.


Yes, an exhaust leak before the turbo can cause low boot. Another possibility is a weak spring in the actuator. As far as I know you cannot get a replacement actuator... you can add an aftermarket universal if yu fabricate a custom bracket or you could add a boost controller (a manual boost controller can be built very cheap!). Get the exhaust leak under control first.
Is the #1 cam the one closest to the fire wall or the one closest to the radiator.
How would I go about building a manual boost controller? I. May have the turbo rebuilt by powerfab with a bigger wheel inside for a little more boost and that way I don't have to modify the flange.

Another thing I wanted to know is how do I put a blow off valve in I live the sound of them and would like to incorporate it into the stock set up with aluminum piping instead of rubber hoses. Is this possable with the turbo being internaly wastegated stock from factory? This is my 1st supra and first turbo vehicle please correct me if I make any mistakes this is something I really neeed to learn.
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Old 01-14-2010, 08:24 PM   #4
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Quote:
Originally Posted by bradenman1 View Post
Is the #1 cam the one closest to the fire wall or the one closest to the radiator.
The culinders and everything else is numbered front to back. Anyway, it's the only thing the valve cover goes up over, you just need to add a little dab of RTV silicone to the tight corner where it comes up.

Quote:
Originally Posted by bradenman1 View Post
How would I go about building a manual boost controller?
Google "diy boost controller"; if you're unsure of the accuracy of the instructions you find post a link and I'll look it over.

Quote:
Originally Posted by bradenman1 View Post
I. May have the turbo rebuilt by powerfab with a bigger wheel inside for a little more boost and that way I don't have to modify the flange.
I am unfamiliar with that company; Make sure they do reliable work. I (as well as most Supra owners) advise not going larger than a 57 trim. Personally, I'd go with a company that has a lot of experience specific to the CT-26.

Quote:
Originally Posted by bradenman1 View Post
Another thing I wanted to know is how do I put a blow off valve in I live the sound of them and would like to incorporate it into the stock set up with aluminum piping instead of rubber hoses. Is this possable with the turbo being internaly wastegated stock from factory?
BOV and WG have nothing to do with one another... neither one will affect the operation of the other. There's nothing to installing an aftermarket BOV, install pipe with proper flange, mount BOV, connect the vacuum hose which ran to the stock BPV, plug BPV's return and the opening on the manifold where the pressure was venting from.

Do keep in mind that loud BOVs are cop magnets (ugh) and you may experience issure when letting of the throttle (stumbling or stalling) as the ECU thinks it's about to receive air which has actually been purged.

Quote:
Originally Posted by bradenman1 View Post
This is my 1st supra and first turbo vehicle please correct me if I make any mistakes this is something I really need to learn.
Heh, oh we will.
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Old 01-15-2010, 12:44 AM   #5
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If you run the vacuum hose correctly the air flow sensor will pick up the air flow changes and there should be no stutter from the engine when letting off the gas from hard accel, learned from doing it wrong the first time ;p
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Old 01-15-2010, 01:00 AM   #6
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If you run the vacuum hose correctly the air flow sensor will pick up the air flow changes and there should be no stutter from the engine when letting off the gas from hard accel, learned from doing it wrong the first time ;p
WTF? You've just DUMPED a large quantity of air. The 7M doesn't use any sort of meter which can see this loss... thus many people experience problems. And vacuum has nothing to do with it at all... Interestingly some people just see heavy richness and some occasional backfiring (postignition). If you have a fuel controller this can usually be compensated for.
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Old 01-15-2010, 01:05 AM   #7
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Thus he got me, lol all I know is I only ever felt a stutter once that was the first time I installed my apexi blow off valve mechanic told me I had it on wrong moved a few hoses and bam it ran perfectly!
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Old 01-15-2010, 02:05 AM   #8
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Quite simply: Overly rich = bad. The goal is NOT to run overly rich when you shift... it causes a big power loss when you finish shifting and get back on the throttle. Personally, performance is more important to me than some cute little whistle.

Some people compromise by installing a BOV AND keeping the stock BPV. This cut's the over rich condition down quite a bit as not all air is being dumped. There's still a loss though.

Anyway, if your car isn't stalling and you're not worried about squeezing every last bit of power out then go with it.... just pointing out that you may experience issues. And if you are looking to squeeze out every last bit of power then you really need to look into a fuel control system anyway (most of which will let you tune out the over rich issue).
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Old 01-15-2010, 05:47 AM   #9
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Quote:
Originally Posted by cre View Post
The culinders and everything else is numbered front to back. Anyway, it's the only thing the valve cover goes up over, you just need to add a little dab of RTV silicone to the tight corner where it comes up.



Google "diy boost controller"; if you're unsure of the accuracy of the instructions you find post a link and I'll look it over.



I am unfamiliar with that company; Make sure they do reliable work. I (as well as most Supra owners) advise not going larger than a 57 trim. Personally, I'd go with a company that has a lot of experience specific to the CT-26.



BOV and WG have nothing to do with one another... neither one will affect the operation of the other. There's nothing to installing an aftermarket BOV, install pipe with proper flange, mount BOV, connect the vacuum hose which ran to the stock BPV, plug BPV's return and the opening on the manifold where the pressure was venting from.

Do keep in mind that loud BOVs are cop magnets (ugh) and you may experience issure when letting of the throttle (stumbling or stalling) as the ECU thinks it's about to receive air which has actually been purged.



Heh, oh we will.
Oh. I was under the assumption that a blow off valve was a waste gate just mounted away from the turbo itself.

Ok so today I took off the valve covers the came look great verry little scoring and pretty clean but I'm going to degrease the valve covers and the cwhile I'm in there.. I also found a few verry dissappointing things in this process ;(

First off there are a few cremped hoses that need to bbe fixed ( no big deal). But then there's a hard pipe type hose that goes from some type of valve into the manifold that crosses over the block. It was hard plastic and wraped in electrical tape. Idk what to call it to get it ordered.

Then after I got all the clutter off the valve covers I took the wires off the sp plugs and 3 of the wires that run from the coil packs broke off on the plugs and on the inside where the plugs are its flooded with oil. What the heck dso I do about this? Iv heard its some what normal for it to happen but its quite a bit of oil in there. Any idea where the oil is leaking in from?

Then I decided to look in the trunk and discovered it is not in existance the entire spare tire holding area is rusted through I can see the muffler and gas tank from the back seat when the cover is out. And the area a little to the right by the fuel pump is starting to rust through to : ) idk what to do about this. This car is turning into more of a project everytime I try to fix something...

Thanks for all the replys by the way . Thewy have been verry helpfull
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Old 01-15-2010, 07:42 AM   #10
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I'm only going to cover a couple point, hopefully someone else will chime in with more info for you.

If you need help with a part, post a picture.

Oil in the plug galley is not unusual when the valve cover gaskets are leaking. That is the most likely source. The other source is the four massive plugs holding down the central cover. Start with getting as much oil out of there as possible with rags and perhaps siphon, then pull the spark plugs and just let the last few drops in each plug recess to empty into the cylinder (I hope there not a lot of dirt in there with the oil). Clean the plugs and wires thoroughly, reinstall the plugs (DON'T OVER TIGHTEN THEM) and run the engine to burn off what drained into the cylinders.

As for the rust, I don't know... The easiest fix IMO would be to cut out what's bad and weld in new sheet... otherwise, if it's more extensive either just cut it all out and weld in a new custom trunk bed or cut one from a chassis at a salvage yard and weld that in.

Check the rear tire wells for rust damage as well.

Your hatch seal is probably leaking if that much water's been accumulating in there.

Yes, cars this old are rarely easy on the wallet.
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