Hey guys, well took the national on a little road trip, i'd say about 100 miles, got off the ram, engine was at about 175 degrees, and oil pressure was like 19psi at like 900 rpms, a real call for concern, so i pulled over and checked the oil, good, yet if i reved it to about 2500 or 3000, it knocked slightly, runs great still, and goin down the road on the thruway, oil psi was like 45 psi at about 2800 rpms, still running fine, are there any main problems with these cars like timing chain related, i know i got a lifter that's bad and tickin, but this does sound like a rod knock. As for cranks to replace this, i'm checkin into reground cranks. Are they a pretty good idea or are there differences in the turbo and non turbo engines? Or should i just send out my crank to get reground? i don't wanna put a crank and all new parts in and have another problem, the engine only has 70,000 miles on it and alot of goodies on it. But yet it still runs fine and since this happend i put i'd say close to 300 miles on it and the sound hasn't gotten worse. Oil psi is no lower than 20 at idle and when cold of course with the oil bein thick it's about 60.Any help would be appriciated. Thanks
If this was my car I woulod take a copression and leak down test to see what shape the rings and cylinder walls are in.(No this would not cause a knock).If that checked out okay I would find out what was causing that knock and fix it.Have you ever looked at an engine that had a rod break.Also when it is knocking it is hammering the bearing and flattening it out.As far as replacing bearings in the engine while it is in the car that is easy.But you have to make sure the bearing journal is not out of round or the new bearings will not last.As far as heavier oil that may help on a cold engine,not on a hot one.Bruce
Before tearing into your engine, you may want to temporarily remove the accessory belt and rev the engine to see if the knock still exist. You may have a pulley, alternator, A/C comp, etc.,, making noise. That's what I did, before determining the engine's #1 rod was knocking. The one thing I did notice (on my broke engine), was there was very little oil in the cylinder head, with the oil fill tube removed. I then removed the oil pan (can be done with engine in car) and started pushing on connecting rods. When I got to the #1 rod, it flopped like a fish (spun bearing). I was told by a machine shop warehouse, that if #1 cannot be turned, I would have to replace the crank (of course, just my bad luck). the machine shop told me #1 rod journal is the weakest. Unfortunately, as I was putting the reground (balanced) crank in , I noticed that the crank was welded on rod journals 3 and 5. I still put the motor together (with doubts), but it runs really great. One thing I would examine if your going to balance the engine, is the harmonic damper. The machine shop bent the interrupter ring (probably dropped it or placed something heavy on it during hot tanking). I hope your engine is not messed up!!
Thanks for your input guys, I wanted to just check out some options to see if anyone else had any other problems that it could be, I guess just trying to convince myself that I don't have a spun bearing, cuz I'm pretty sure I do, the oil psi was never that low, and I figured that it'll be pretty cheap and easy for me to rebuild the engine in engine class at college here, I'm pretty familiar to spining bearings, I've done it in now all 3 of my vehicles already. By the way, I'm looking at some cranks and what are the forging numbers? I found a few for like 200 bucks ground .010 mains and rods with bearings, not bad considering the one I paid for one car was 225. I'm planing on punching it out maybe .020 or .030 over depending on how the bore looks, hopefully pretty good. Regrind the heads, and probably look into a cam, any ideas? I'm lookin for a cam that will give me a little more power, but still be a good street cam/strip cam. Any suggestions are really appriciated since I'm still new to these cars. Thanks alot. Also I have a cheetah turbo on my car that is in need of some bearings/seals. Where can I get those? thanks again guys.
Had my turbo rebuilt by a company in Cameron Park CA., Turbo Power, tel.:530-677-2233. Owner name: Dobie. Did a fantastic job on rebuilding my turbo!!
Casting numbers don't really mean anything, since the same casting was used in N/A and turbo cars. Look for the rolled fillets on BOTH the mains and the rods. For more casting numbers and part numbers, look at:
http://www.gnttype.org/general/v6hist.html
I wouldn't overbore, unless it really needs it due to cylinder taper. With the cam, stay SMALL don't go huge ... it'll hurt more than help. 206/206 is a good grind ... 200/200 is a good grind. Much bigger and you soften up the bottom end and better have the rest of the combo matched.
Cheetah turbo was made by Turbonetics, so contact them. They usually have a lot of kits and parts. Or contact Limit Engineering or Precision Turbo and Enginer.
Well guys, I finally got to tear down the engine. Just like I suspected, someone's been into that engine before me, and one hell of a chop job!!. Main problem was excessive piston-bore clearance,dirt contamination on the bearings from a hole in the top of the timing cover. The head gasket was all blown out and messed up. I bought the car in Utica NY, and on the visor, it has a cotton performance sticker on it. Also the car has GNX fender vents on it(not my add on)and it's a t top car. So if the guy who built that engine is on here, Nice job!!(sarcasticly)Sorry about that. The plans are a new stock crank,all new bearings,bore it to .030,mildly porting the heads. Now the only question is, what exact grind would be good for street/strip performance. I'm trying my best to pay for these parts while goin to college. This car was mechanicaly beat, and i'm tryin to bring her back. Any help would be appriciated guys. See ya later fellow TR's
I'm using a Poston 107 cam, 202*@.050 and .430 inches of lift. Lobe centers are 107. I don't know what part of the country you live in or are concerned about smog checks, but I noticed alot of mild street strip cams widen the lobe centers to 110* to 114*. If you live in an area that checks for Nox, the wider lobe separation increases cylinder pressure and with it Nox. In California, last year ARB reduced the Nox cutpoints by 15 percent (maximum regulatory amount without legislative intervention). That puts passing Nox standards around a 1000 parts per million. Therefore, I tried to stay with a cam that matched or closely matched factory lobe separation. The other cam I looked at was a Lunati 206 cam. Just my .02 cents