Hi all, New to the forum, so greetings to everyone. I recently acquired a 1989 Jap-spec N.A./manual z32. Have replaced timing belt, water pump and thermostat, the vehicle was purchased with a bad water pump. I have travelled less than 5km in 3 or 4 weeks since purchasing the car (a few blocks for diagnostic purposes) as I dont want to cause any serious or further damage. I have also searched this and other forums fairly extensively to try and get an idea of what is wrong. The main issue is a fairly loud ticking (what i interpret as a tick, I could be wrong) at idle. The noise is not present at start-up, the engine always starts after 1 or 2 cranks and sounds quite healthy. Over the next 30seconds to 2 minutes or so, the noise becomes quite loud and is very noticable around the whole car, not just the engine bay. The sound appears to be coming from the pass. side valve cover (again I could be wrong here). The ticking is consistent with the revs, and fades away at higher revs (2500-3K) but returns as loud as ever when returning to idle. Oil has been changed twice, BLACK, THICK, HORRIBLE oil was drained, filter was changed and topped up with nulon 10w-30. Nulon oil was changed out after about a week (a few Kms travelled and maybe 5-10 start-ups/idle to operating temp) and replaced with shell helix 15w-50. The week old Nulon was very black but slightly less disgusting. Some sludge is noticable on cam under oil-cap. Although she sounds healthy I fear it has been a long time since the oil was changed. All spark plugs were fouled with dry, sooty carbon. After being replaced with new NGKs (PFR6B-11) and run only once to warm the engine before a compression test, plugs on cylinder 2 and 6 were fouled with oil. cyl 6 was the worst. All cylinders are firing, with the occasional misfire at idle (seems to be clearing up, air filters are DIRTY, definitely one of the first things to be replaced when i can find suitable replacements). Exhaust is slightly smokey sometimes, slightly oily smelling, slightly rich sometimes.. its a little hard to tell. compression results: cyl1: 195 psi (220 cold) 2: 160 (150 cold, 130 wet (battery may have been drained by this point)) 3: 190 (200 cold) 4: 165 (165 cold) 5: 190 (200 cold) 6: 200 (200 cold) What is the likelihood that this is a valve issue? Would I expect to see even lower compression on cylinders 2 and 4 if there was a head gasket issue in that area? According to my reading, these compression results arent too bad? Thoughts? Recommendations? Should I pull the plenum and valve covers and check out the valves? I guess I already know the answer to this question, just hoping for a little insight from the more experienced around here before I start diving in further. As for engine/oil treatment/additives, I have read many different opinions on this forum and others, I guess some insight into what you would try personally is what I'm after. I have never owned a V6, or a car with a large, loud exhaust so diagnosing the health of the engine by ear is quite difficult for me, and whether power is low I have no idea as I have nothing to reference against. There is a metallic type sound at higher revs (4-5K) under load, unsure if this is pinging or just exhaust noise. I am located in Wynnum North, Brisbane if anyone is close and available to lend another set of ears. Thanks for any input, Brenton
the numbers are not bad but there is still too much variance between the cylinders. some might consider a 20psi difference already on the high side and you've got 35 psi difference. does the car blow smoke under load? if so it's the rings. sounds like it's already burning a bit of oil if you can smell it in the exhaust. any metallic sound is a worry and if you're hearing it under load above 4k you definitely want to make sure it's not pinging else it'll do a fair bit of damage pretty quickly. ideally you'll want to make sure it's not leaning out but you need a dyno or someone with a exhaust sniffer monitoring the AFR when you load it up. i do have a dodgy valve in cylinder 1 not closing. it's been progressively getting worse and compression dropped by 90psi. pretty certain it's a dodgy valve spring. this causes a very noticable pulsing misfire at idle and the car has dropped a bit of power. it does tick but only when cold, harder to notice when warmed up. my valve problem does not blow smoke nor can you smell oil in the exhaust. overall sounds like it's been neglected and it's going to take a while before you flush all the old crap out of the engine. you can chuck in a engine flush additive and just get cheap mineral stuff. 40 or 50 weight and do changes every 500kms. if you have bad rings the lighter oil will more likely get through and get burnt by the engine. that might be a good indicator too.
thanks for the quick response, yet to test for smoking under load, will have to borrow the mrs eyes later today when she returns, it wasnt noticable in the rear view mirrow when driving (I did keep an eye out, so it wasnt 'suburban block smoke-out' smokey) but I still cant answer that definitively. after having a quick fiddle just now, there seems to be a fair amount of smoke while revving with no load, this seems to be worse than it was a few weeks ago after I finished up the water pump and timing belt (the car really hasnt run much at all since I got it). From memory, the oil smoke got worse after the compression test. the exhaust smelled rich initially, after comp test it smells oily. I put this down to the wet test, and needing to burn off the oil that was in the cylinder for the test. Generally, would you say that injected oil (from a wet compression test) would take a few strokes to clear or would it be more like a few Kms? Please excuse my ignorance I am a bit confused by the low compression in 2 and 4, yet oily plugs in 2 and 6. if the compression in cylinder 6 is high (200) and the plug was more oil fouled than the one from the low compression cylinder, would that point to a valve problem in cyl 6? (cyls 2 and 4 aside) The misfire is quite noticable, but not steady, some are more severe than others but there is definite gaps in the exhaust note.
Yes the oil smoke would definitely be the wet test. It'll burn off completely pretty quickly. How far have you driven it since the test? If it continues the oil is coming from elsewhere, could just be oil in the plenum & dodgy PCV valves. You could do a quick check for oil in the intake plenum by taking off the black balance tube at the back of the plenum. Re cylinder 6, could just be oil sucked in through the plenum since it's most likely to pool near the back of the plenum.
Ive driven less than a km since the test, and started up and idled for a few minutes maybe 3 times. I did notice oil in the plenum when taking the balance pipe off for the compression test, the thought hadnt even crossed my mind. Thanks for your help will pull the plenum when the new gasket arrives, clean it out and do the bypass then see how things go from there. Thanks again for the help
I'm thinking the ticking could be injectors. Specially if the car has been neglected as it has? hmmmmm.......when doing a comp test today, I noticed oil in the spark plug chamber of no:6 (or the rear left bank cylinder). Will check the plenum before I replace the balance tube
You can actually hear the loud ticking over the injectors (the injectors are fairly loud but no single one seems significantly louder than another and they are fairly consistent from startup all the way to operating temp, the other tick is loud, but not evident for the first 30 seconds or so. Using a stethoscope the closest I can get to the sound is the passenger side valve cover from the side of the engine (or around there anyway). The noise is more noticable from around the passenger side front wheel than it is with your head above the engine (I don't know if its actually louder here, but its less drowned out by other engine noises). It is also very noticable around the whole body with the bonnet down, i.e. it is loud. sorry to repeat myself just trying to make things more clear. Thanks for the suggestion though, any and all are appreciated.
Sounds like you have an engine that was way over due for a serivce. By your description, the noise does sound like a lifter tick which is also consistent with a lack of servicing, the lifter check ball becomes blocked with sludge. No way to repair this other than an ultrasonic clean or replace with new. Do not use any type of engine oil additive that claim to clean the engine, all are laced with negative effects the companies don't want to tell you, most of which lead to dramatically shortened engine life. The other issue I see is the 2 cylinders with low comp are beside each other, often indicating a leaking head gasket. Remember you don't need alot of pressure loss to have a leak, it could only be minor. Also worn intake valves are par for the course with a VG, they are almost always beat in very badly. You can not see this with out removing the heads. A leak down test will indicate where your issues are more than a comp test will, might be the next step before you tear it apart.
Sounds like it has run a rod bearing, if it were a lifter it would do it straight after the engine starts and wouldn't go away at higher RPM. The most common bearings to go are five and six so the noise would come from the back of the engine. The poor condition of the oil obviously shows a lack of servicing but contrary to what you would expect the thick tar like fifty billion kilometre oil normally helps lifters seal and stop making noise (until you do a service) the bearings are normally the first thing to suffer from this rather than the lifters. If you still have the original oil filter from the service cut it open with a can opener and pull the paper out of it, if it's got bearing metal in there she's smoked.
I agree with Eric and Jinxed, I buy cars that are in less than perfect condition and often the hydraulic lifters are very noisy, in fact one car I could have sworn it was a small end bearing. Hardest thing is finding which one is noisy, so clean or replace all of them. Find out what the the compression issue is as it might require engine out and all jobs on the VG30 are easier with the engine out. A2zed (Eric) in my opinion, does a great job if you need help. One other piece of advice, DONT take it to your local mechanic, unless hes a Z32 enthusiast.
