Hey guys, My TT hasnt been running 100% for a little while now. I've had a slight misfire from no 1 cylinder. Over the past couple of months I replaced most of the loom (including plugs etc) and a new coilpack. Today I went down to the shops to get a haircut and the z was running crap and on 5 cylinders. Got home. Pulled the coilpack connector etc and the cylinder was not firing properly (no change in idle when remove coil plug). So I decided that i finally needed to get around to doing a compression test. Hooked up my compression tester etc, here are the results: Cylinder 1: 118psi max - 170psi wet :vomit: Cylinder 2: 152psi max Cylinder 3: 155psi max - 180psi wet Cylinder 4: 150psi max Cylinder 5: 155psi max Cylinder 6: 150psi max Now I realise why I had problems with the idle and slight misfire. The rest of the cylinders were trying to compensate for cyl 1. I only did a wet test on Cylinders 1 and 3 coz I didnt see much need doing the rest as I've located the problem cylinder. I would assume the rest of the cylinders would also go to around 180psi with a wet test. So I suppose cylinder 1 must have bad piston rings. And the rest of the cylinders must have rings that are on their way out too I suppose (but not as bad as cyl 1). Valves couldn't be a problem would they? Coz if it was I thought the compression wouldnt increase with the oil test. This would rule out headgasket too hey? So yeh not an awesome result. I suppose an engine pull will be on the cards now. Now is my question: Can I just replace the piston rings? (assuming pistons are undamaged etc). I'm a student so i'm not keen on spending a fortune on forged components. I mainly just want to restore the compression to the normal level. I'm pretty handy with cars so pulling the motor apart is not a problem. But ive never done rings before! I'd appreciate any input. Thanks guys! Cheers, Rob
bad luck most likley your rings on number 1 . U might get away with just new rings but u will have to pull the motor and measure everything (outof round etc ) if ur going to all the trouble of pulling the motor i would at least put some forgies in there . leave the rods stock there preety tough. Regards Trev
As Ugame says iv'e seen compression much worse and still run ok, If your pulling a coil pack plug and it runs no different then i'd be fixing that first to get it running right. Rings can be replaced, but its an engine out job to do it Can be done with dropping the front end and removing the head, both long and time consuming and if you are going to go to that trouble i would pull the engine and give it all a freshen up. There's a few of us on here with engine rebuilding experience that can walk you throught it if you decide to go down that path, but your going to have to be prepaired to spend a few dollars
Thanks for the replys! So you think I should probably just leave it alone? I just got some prices from Coz etc and to get a new set of oem piston rings and a complete engine gasket kit would be around $500 plus postage. The labour doesnt bother me - i was planning on doing it all myself. But is there likely to be specialist work needing to be done that I can't diy? I already have engine crane etc so I would just be pulling the engine to work on it properly. The main reason I want it running right it because i just bought an ebc and I want to run just around 12 psi to start off with. I just didnt want cylinder 1 to cause any problems. But i've never replaced rings b4 and I appreciate any that wisdom forum member may wish to give btw I dont think the coilpack is the problem. its just that the cylinder had bad compression which resulted in imbalance. I had previously fixed all the coilpack connectors etc
mine is worse and runs sh!t Cylinder 1: 52psi Cylinder 2: 100-150psi somewhere Cylinder 3: 100-150psi somewhere Cylinder 4: 100-150psi somewhere Cylinder 5: 100-150psi somewhere Cylinder 6: 100-150psi somewhere you will still get a year and a bit out of your engine mate so you have plenty of time to buy one and rebuild it yourself great project oh and that cylinder with the lowest comp will be getting fuel just dumped into it, your economy isnt going to be that good. watch out for the hicas light as it will come on soon if it hasnt already
replacing the pistons dyi?? yeah, you do that when rebuilding your engine. along with new gaskets etc....you might as well if you are willing to do it all yourself either build to stock or if you have the money and want to, this would be a great time to get rods, bigger turbos etc build it to about 300-350rwkw
Agree with Wiz... ...I've seen much worse compression figures and still run ok. Even with these figures pulling a plug should have a noticeable effect, fix this first and re-evaluate
What they're saying is it's a big job just to replace the rings, so either leave it until you can do everything at once or do it now in one go. Personally i would leave it until your ready for a complete rebuild.
ahh cat light sorry, lmao i was reading the hicas lock bar thread in fsbb just before this lmao my bad yeah the cat light, you know what i meant lol
Thanks for all the input guys. Must appreciated. I'm still leaning towards replacing the piston rings. At this stage I really don't want a performance build nor can i afford one (still a student). I do intend on doing that down the track when I can afford to buy a spare z engine to work on over a long time. But thats not for at least a year probably more. I dont really want to put off fixing the z coz im moving to melbourne in december and won't have anywhere to work on the z for quite a while. I plan to have it in tip top shape before i make the big move. Also there are a few other things I want to do at the same time with the engine out - remove the rest of my egr, some bastard turbo hoses, rear main seal, valve stem seals etc. Probably replace rod and main bearings at the same time as they're pretty cheap. I am fortunate to have a VZ Ute to use as a daily so having the Z off the road for a month or so won't really matter that much. But I won't be starting the engine pull for another couple of weeks or so. I will be sure to start a thread with pics if i ultimately decide to go down this track.
If you're just doing rings and bearings it 'might' be possible to not pull the engine? Drop the cross member and sump? I'm not 100% sure but someone here may know for sure... would make it loads easier. Good luck.
Yeh but i'd get sick of lying under the car with stuff dripping on my face. I got the engine crane so pullin the engine is not a biggie.
it could be just a stuffed lifter like mine was except I think what caused that was very worn valves (early Z32 problem) so need to pull the heads anyway.
