this one has me stumped

supradaddy0803 · 01-03-2007, 02:54 AM

To start I have checked and the knock is coming from the top end not the bottom. Ok when I first got my car it ran like crap it is a 87 n/a 5spd so i decided to tcheck a few things one being the timing when i got the chance to actually check it (i work out of town a lot) i noticed it was about 3 degrees before which yes is real slow I know now it is right dead on 10 degrees and now it has a preignition knock of sorts under load about 2000 to 3000 RPM it gets a destinctive knock from the topend too light of a sound to be from the bottom plus to quiet to be a rod knocking sounds more like valves hitting or a wrist pin maybe number 2 or 3 so i pulled the distributor to check the pickups on it shop manual says between g1 and g-, g2 and g-, and ne and g- needs to be 140- 180 ohms mine is 225 to 230 which it calls bad i am gonna check the timing belt but I am sure it is on but my question is is this a normal problem and if so can i fix the distributor pickups without buying a new one. I have good oil pressure about 6 at idle and over 40 at higher RPM only mods done to the car are a K&N filter and a HKS dragger catback. Also I replaced the distributor rotor because it was loose and looked like it had been hitting the points and it has a new cap. any help would be greatly appreciated and it may take me a few day to get back to you with answers because I work a lot out of town I have just run out of ideas and would really like to not have to rebuild if it comes to it.

rnoswal · 01-03-2007, 12:35 PM

Hard to say for sure. They are cars that have a valve clearance that has to be adjusted by replacing shims. That will cause a ticking noise if the gap is too large. One way to check for wrist pin noise is to pull a sparkplug wire on the suspected cylinder and listen to see if the noise goes away. The other area is piston slap. If the cylinders are really worn they can make a noise, but I think the only way to check it is a leak down test or pull the head and actually measure the cylinder, which is a severe pain in the ass.

It does sound like your measurements are out, but if it still runs without missing then it should be OK. You might have a LOT of carbon build up in the intake/exhaust and top of the piston which will cause quite a raise in compression Then the fuel might detonate because of not enough octane at the new timing mark you reset it to.

The oil pressures sound about right, but you might want to change the oil and filter and put a higher viscosity oil in to see if it moves up any. Let us know how the noise goes and if you make any progress.

Russ

supradaddy0803 · 01-04-2007, 01:23 AM

yes the head is a pain in the behind I had a 86.5 and rebuilt the whole motor and the head was the funnest part to pull out from under the hood needed me and someone else on the other side to lift it. The sound is kind of like the when a motor deisels you hear that clack noise it is kind of like that it is a better way to describe the noise all together. The shop manual has no trouble shooting for a knock so I am kind of stuck. As for oil I am using Quaker state high mile 20w- 50 because of the fact it has leaking valve guides and it has 150000 miles on it so the oil is decent not like royal purple or anything or racing oil. my 86.5 never really had high opil pressure or anything. I just need to know if this is going to get expensive again like my 86.5 because I might have enough money to buy a different motor like a 1JZGTE 5spd just trying to make it cost effective so I can delegate funds towards it.

01-03-2007, 02:54 AM	#1
supradaddy0803 12psi boost Join Date: May 2006 Location: Athens, TX Posts: 308	this one has me stumped To start I have checked and the knock is coming from the top end not the bottom. Ok when I first got my car it ran like crap it is a 87 n/a 5spd so i decided to tcheck a few things one being the timing when i got the chance to actually check it (i work out of town a lot) i noticed it was about 3 degrees before which yes is real slow I know now it is right dead on 10 degrees and now it has a preignition knock of sorts under load about 2000 to 3000 RPM it gets a destinctive knock from the topend too light of a sound to be from the bottom plus to quiet to be a rod knocking sounds more like valves hitting or a wrist pin maybe number 2 or 3 so i pulled the distributor to check the pickups on it shop manual says between g1 and g-, g2 and g-, and ne and g- needs to be 140- 180 ohms mine is 225 to 230 which it calls bad i am gonna check the timing belt but I am sure it is on but my question is is this a normal problem and if so can i fix the distributor pickups without buying a new one. I have good oil pressure about 6 at idle and over 40 at higher RPM only mods done to the car are a K&N filter and a HKS dragger catback. Also I replaced the distributor rotor because it was loose and looked like it had been hitting the points and it has a new cap. any help would be greatly appreciated and it may take me a few day to get back to you with answers because I work a lot out of town I have just run out of ideas and would really like to not have to rebuild if it comes to it.

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01-03-2007, 12:35 PM	#2
rnoswal Lexus & 550's Join Date: Apr 2005 Location: Bossier City LA Posts: 556	Hard to say for sure. They are cars that have a valve clearance that has to be adjusted by replacing shims. That will cause a ticking noise if the gap is too large. One way to check for wrist pin noise is to pull a sparkplug wire on the suspected cylinder and listen to see if the noise goes away. The other area is piston slap. If the cylinders are really worn they can make a noise, but I think the only way to check it is a leak down test or pull the head and actually measure the cylinder, which is a severe pain in the ass. It does sound like your measurements are out, but if it still runs without missing then it should be OK. You might have a LOT of carbon build up in the intake/exhaust and top of the piston which will cause quite a raise in compression Then the fuel might detonate because of not enough octane at the new timing mark you reset it to. The oil pressures sound about right, but you might want to change the oil and filter and put a higher viscosity oil in to see if it moves up any. Let us know how the noise goes and if you make any progress. Russ

01-04-2007, 01:23 AM	#3
supradaddy0803 12psi boost Join Date: May 2006 Location: Athens, TX Posts: 308	yes the head is a pain in the behind I had a 86.5 and rebuilt the whole motor and the head was the funnest part to pull out from under the hood needed me and someone else on the other side to lift it. The sound is kind of like the when a motor deisels you hear that clack noise it is kind of like that it is a better way to describe the noise all together. The shop manual has no trouble shooting for a knock so I am kind of stuck. As for oil I am using Quaker state high mile 20w- 50 because of the fact it has leaking valve guides and it has 150000 miles on it so the oil is decent not like royal purple or anything or racing oil. my 86.5 never really had high opil pressure or anything. I just need to know if this is going to get expensive again like my 86.5 because I might have enough money to buy a different motor like a 1JZGTE 5spd just trying to make it cost effective so I can delegate funds towards it.