There is no bearing between the gear and cam, or any cam bearings at all for that matter. It is very unlikely that you have no bent valves. And a tight camshaft is a good indication of a very overheted engine. Do what chrispy says, put a new belt on and comp test it before you go any further.
wow.. well I spose it is similar to that... in a way? that looks a fair bit worse than what happened with my timing belt. My timing belt is only missing like 3-6 teeth off it max. thats the only damage. besides that the rest of the timing belt is in perfect condition. I'm hoping i've gotten lucky and nothing has been damaged too much. But just to make sure i'll be checking as much as I can to make sure the valves are okay and the rest of the engine is undamaged.
Thanks for the advice. I'm gonna have to investigate it a bit further since there isn't a bearing. or just look for what may be causing it to seize up . if it makes any difference.. it's the camshaft on the far right hand side of the engine.. the exhaust valve side. not the camshafts in the centre. Would it be much help if I could show you pictures of the camshaft, valves and the damage done to the timing belt?
Yep, sure would help to see some pictures Won't be able to tell much about the valves with the heads still on though.
Great idea.....if you are anywhere in the vicinity of Vermont, take it (them) to Dontex. Joe and Warren will help you sort them out......they're awesome 300zx expert guys and we couldn't live without them. Good luck!!!!! Karen and David
Here's a few pictures.. Not sure if they'll be of much use or not though. But it may be worth looking at. Exhaust Camshaft Timing Belt 1 Timing Belt 2 Valves / Camshaft Good 300zx Broken 300zx
Hmm, heads look a bit sludgy... How many k's? I haven't seen a timing belt do that before, but I haven't seen many failed ones before. How are the idler bearings? Do they rotate freely by hand? All three? Does the tensioner still move if you put the little bolt in (do it up about half a turn every 10-20sec otherwise you WILL break it if you go too quick). Where abouts was the striped section of the belt? On one of the cams or down on the crank sprocket? Do you know any history of what happened to the engine? When/how the damage occurred? And just so you know. The closeup of the cams, the round things that the cams touch are the hydraulic lifter. They adjust valve clearance with oil pressure. The bottom of them touch the top of the valve. I don't believe there is a way of checking for valve damage without removing the heads or doing a compression test.
I have a tt here that done the same as that. Cause was a seized cam due to overheating. Engine blew a heater hose and the driver just kept goig until it stopped. The engine had no bent valves but the heads were extremely warped. It was only pure luck that it had no bent valves as we all know.
Warren owns the shop Imbesi is the expert, yes there good, and at over 90 per hour they would want to be.
A simple way to test whether there is valve or piston damage is to loosen the camshaft bearing caps, allowing all valves to close. Remove spark plugs and pressure test each cylinder using compressed air at about 200kpa. If each cylinder holds pressure you are good to go, fit new timing belt as per tech sheet.
Thanks for the advice guys, has been good as far. I'll most likely try some of the suggested solutions when I next get the chance. Uhm just to answer a few of the questions that have been asked. The engine in the pictures shown has done 139,561 k's so just under 140,000. Where as the engine in the smashed up zx has only done 77,100 k's. I'll try moving the tensioner and seeing where the damage on the timing belt has occured in relation to the cogs etc when I work on the car next. As for history of the engine... I bought the car off a mechanic in Melbourne. The car was sent to him from a place called The Z Shop, I think? The old registration used to be "MONAA". It was previously owned by a pensioner, who hadn't driven the car for a while (not sure on how long.. could've been between 6month and a year.) Then eventually he took it for a drive, which is when the damage occured. The mechanic I bought it off said that, the damage may have occured because the car was left sitting around without being used for a while and something about the timing belt needing to be replaced every so often. I think he said 100,000 k's? Anyways.. the pensioner already owed the mechanic money, and didn't wanna go through with having the car fixed, so thats when I travelled up to Melbourne from Mildura to buy it. Hmm if I lived close enough to any Z specialists I would probably, most definetly get them to have a look at it for me. But i'm not too close to Melbourne so it makes things a bit difficult. I'm thinking my best bet would be to do a compression test as you guys have already mentioned. So all I need to do is remove the camshaft, make sure there is no pressure on the hydraulic lifters (the things that control the valves.) therefore meaning the valves will all be closed, remove the spark plugs and then put some compressed air in the holes where the spark plugs came from?
Okay.. I haven't Done a compression test yet. However... today I removed the camshaft. Upon inspecting the camshaft I noticed that where the camshaft sits in the first bracket.. nearest to the sproket.. the surface on which it is meant to slide is covered in some rough metal. Also the surface opposing the camshafts surface.. on the head is rough. The hole where the oil is meant to come through to lubricate the camshaft is blocked by scoured metal I hope my description is of some use.. as I was not able to get a hold of a camera yet. But will try to get pics of it in the near future. I am now considering asking a machinist if it is possible to remove the scoured rough metal surface inside the camshaft chamber as well as on the camshaft itself, hopefully to get the camshaft moving smoothly and freely again. My guess is that the engine hasn't had the oil changed over regularly, hence the sludgyness. and because the oil hole that lubricates one of the camshaft's contact surfaces has not been well lubricated.. it has caused the surface to become rough and seize up. Thus in turn damaging the timing belt. ... as for the crashed zx.. we have connected up some more wires.. the car now constantly beeps at me. however turning the key still doesnt start the engine. I'm suspicious of the ignition somehow being locked out.. maybe due to a security system perhaps? I have no idea
Looks like that engine will require camshafts, bearing caps and heads!! and you havent even got the heads or sump off yet. Good luck but this engine may be good for a few spares
I've got spare camshafts, if not i'll probably just buy new ones. And i've got a spare head.. but I imagine the current one could be machined/smoothed back so that it was smooth again. Or maybe even put a brush on it or something. I believe the engine is still good. just a few minor things wrong. If not I've always got a spare one. [TIS]
It is odd that the engine has seized a camshaft journal, that looks like it was caused by loss of lubrication. I would be having a very close look at the rest of the engine, especially the crankshaft.
Took the camshaft to the engine reconditioners today. He said that it would be best to swap the engines over, as the damage to the head would mean that I need to remove the head.. in order to get it line bored, and it would require the metal to be built up and then bored out etc.. plus as drz400y said the engine might be suffering other damage, and I'm a bit skeptical about the degree of the damage as well. Especially since the engine reconditioners said that metal may have been sucked through the oil hole.. and may have gone through the turbos.. and so on. So now.. the next step will be to take both engines out. Then I'm thinking of getting the engine from the wreck and getting it reconditioned, as I plan on modifying the engine in the future and I feel as though this would be a critical step in ending up with a good reliable engine that can still make power.
Hey, I've been working on the engine in the wreck now.. focusing more on it than the engine with the broken timing belt. So far i've gotten then engine to the point where it will make "rrr.rrr....rrrr" noises... as if it wants to start... but it just won't reach the point where it wants to idle. prior to this the car used to beep.. but i got it to this stage by bridging some of the electronic components in the starter relay. If anyone could point me in the direction to get the engine idling I would be most grateful. Thanks
Could it possibly be something to do with spark plugs or some sort of inhibitor system thingy? There is fuel coming through the fuel lines.. and it is under pressure as well.. so fuel must be getting to the engine.
Hey guys. Just an update on how my 300zx is going. The engine in the GOOD zx is still sitting with the cam taken out on the passenger side and a damaged head. I am going to buy a new head and replace it. get a new timing belt on it and service a few things while im at it. Then clean the black oil out of it and put some cleaner stuff through its system. Then hopefully it will start. As for the WRECK zx.. I been playing around with it for a bit now. did a diagnostics check and found error 13. coolant temperature sensor. brushed some of the corrosion off it.. attached the radiator and put some water through it. and it started working. Fcpu wasn't bolted to the car. so fixed that also to get it earthed. Bit of fresh petrol and a little spray of aerostart and it started working! So I'm hoping to take that engine out of the wreck. now knowing that it works.
