Very low compression

paulmicin · 03-23-2008, 11:15 PM

i recently bought a 89' turbo and i ran a compression test to find out why its smoking. no. 1 cylinder has 50 psi while the rest are within spec. I poured some oil in no.1 and it jumped to 70 psi so im pretty sure its a bad piston ring. So i was just wondering what are my options. How hard is it to change piston rings myself or how much would a mechanic charge. Also would it just be cheaper to buy a new engine? I can get one for about 1k.

Benesesso · 03-24-2008, 12:45 AM

Could be a BHG. Have you checked?

supradaddy0803 · 03-24-2008, 03:36 AM

Doing the piston ring by your self (I am considering that you have a little mechanical background) sucks. I rebuild a n/a 7m a long time ago and there is no easy way to do just that. If you can get a new motor for 1k I would say shop around because I have seen 7mge for like 500 and 7mgte for like 750 to 900. Just remember if you go the new motor route check the HG and possibly replace it with the motor out to save you some headache down the road. You dont know how that crazy Japanese guy treated that motor or whoever you get it from. But in the mean time seeing as you will have to pull the head anyways then pull it. Check the valves first oil will make them seal up a bit as well usually they will go before the rings do most of the time and they are easier and cheaper to fix. Also check the head gasket if it is bad change it you can drop the pan just enough to break the rod bolts on number one then just push it out the top and inspect it. Sad thing is you cant just buy the rings for one piston they come as a set and if you went this far might as well hone and replace them all. Well I think I have exausted myself and your eyes OH YEAH if it is a 7mge you want parts to I have one sitting that has good rings and vlaves.

paulmicin · 03-31-2008, 02:57 AM

Thanks for the advice. I'm changing the head gasket right now and i cant seem to reach the bolts for the turbo oil line. i have everything off except the turbo and ex. manifold. anyone know how to remove the turbo?

Benesesso · 03-31-2008, 03:02 AM

Those bolts are real tough. I ended up cutting the lines off, and then had to buy a good used set. I'll see if I have any photos.

mkiiisupra · 03-31-2008, 05:38 AM

Bishop's 92T Supra Page

CyFi6 · 03-31-2008, 08:05 AM

Quote:

Originally Posted by paulmicin

no. 1 cylinder has 50 psi while the rest are within spec. I poured some oil in no.1 and it jumped to 70 psi

20 psi is just around specs for the jump in psi with a wet test. Even brand new motors will jump considerably in compression when doing a wet test. I wouldn't say your rings are bad. Try a wet test in the other cylinders and see how much they jump up.

paulmicin · 03-31-2008, 09:16 AM

Alright i got it off finally but i had to use a special tool.

I was also wondering if this is the stock fuel rail.

might as well post the progress

paulmicin · 03-31-2008, 10:00 AM

What type of socket do i need for arp head bolts?

paulmicin · 03-31-2008, 09:13 PM

The head already has arp bolts/studs whatever the difference is.i dont have a socket that will remove them.
btw, i already have this

03-23-2008, 11:15 PM	#1
paulmicin 3" Exhaust Join Date: Oct 2007 Location: Norwalk, Ca Posts: 52	Very low compression i recently bought a 89' turbo and i ran a compression test to find out why its smoking. no. 1 cylinder has 50 psi while the rest are within spec. I poured some oil in no.1 and it jumped to 70 psi so im pretty sure its a bad piston ring. So i was just wondering what are my options. How hard is it to change piston rings myself or how much would a mechanic charge. Also would it just be cheaper to buy a new engine? I can get one for about 1k.

03-24-2008, 12:45 AM	#2
Benesesso 3" Exhaust Join Date: Nov 2005 Location: Phoenix, AZ Posts: 145	Could be a BHG. Have you checked? __________________ "You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein 1988 and 1990 Turbo Supras

03-24-2008, 03:36 AM	#3
supradaddy0803 12psi boost Join Date: May 2006 Location: Athens, TX Posts: 308	Doing the piston ring by your self (I am considering that you have a little mechanical background) sucks. I rebuild a n/a 7m a long time ago and there is no easy way to do just that. If you can get a new motor for 1k I would say shop around because I have seen 7mge for like 500 and 7mgte for like 750 to 900. Just remember if you go the new motor route check the HG and possibly replace it with the motor out to save you some headache down the road. You dont know how that crazy Japanese guy treated that motor or whoever you get it from. But in the mean time seeing as you will have to pull the head anyways then pull it. Check the valves first oil will make them seal up a bit as well usually they will go before the rings do most of the time and they are easier and cheaper to fix. Also check the head gasket if it is bad change it you can drop the pan just enough to break the rod bolts on number one then just push it out the top and inspect it. Sad thing is you cant just buy the rings for one piston they come as a set and if you went this far might as well hone and replace them all. Well I think I have exausted myself and your eyes OH YEAH if it is a 7mge you want parts to I have one sitting that has good rings and vlaves. __________________ 1987 supra NA 5 speed 1JZGTE swap Tokico Illumina 2 and Eibach springs Tokico pillow blocks Suspension Techniques front and rear sway bar HKS super dragger cat-back exhaust plus test pipe Greddy Profec B spec 2 boost controller HKS type 1 turbo timer Supra sport solid steel drive shaft Walboro 255 fuel pump JZA70 Front end mod 18" Volk Racing AV3 18x8.5 front 18x9.5 rear

03-31-2008, 03:02 AM	#5
Benesesso 3" Exhaust Join Date: Nov 2005 Location: Phoenix, AZ Posts: 145	Those bolts are real tough. I ended up cutting the lines off, and then had to buy a good used set. I'll see if I have any photos. __________________ "You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein 1988 and 1990 Turbo Supras

03-31-2008, 05:38 AM	#6
mkiiisupra Lexus & 550's Join Date: Sep 2007 Location: Las Vegas, NV Posts: 570 Blog Entries: 1	Bishop's 92T Supra Page __________________ 1990 Toyota Supra Turbo A/T ------------------------------------------------ Questions about oil? take a look http://www.supramania.com/aehaas/

03-31-2008, 02:57 AM	#4
paulmicin 3" Exhaust Join Date: Oct 2007 Location: Norwalk, Ca Posts: 52	Thanks for the advice. I'm changing the head gasket right now and i cant seem to reach the bolts for the turbo oil line. i have everything off except the turbo and ex. manifold. anyone know how to remove the turbo?

03-31-2008, 09:16 AM	#8
paulmicin 3" Exhaust Join Date: Oct 2007 Location: Norwalk, Ca Posts: 52	Alright i got it off finally but i had to use a special tool. I was also wondering if this is the stock fuel rail. might as well post the progress

03-31-2008, 10:00 AM	#9
paulmicin 3" Exhaust Join Date: Oct 2007 Location: Norwalk, Ca Posts: 52	What type of socket do i need for arp head bolts?

03-31-2008, 09:13 PM	#10
paulmicin 3" Exhaust Join Date: Oct 2007 Location: Norwalk, Ca Posts: 52	The head already has arp bolts/studs whatever the difference is.i dont have a socket that will remove them. btw, i already have this

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