Need some advice... broke the timing belt

[Danspeed1]

We were out in Jersey yesterday and were accelerating off an on ramp. My girlfriend was driving my 1995 Monte Carlo Z34 3.4L DOHC V6, so she wasn't hammering on it,... I'd figure 40% throttle. The car revved up all of a sudden and then just shut down. I couldn't get it started but I had an idea of where this was headed. No metallic sounds before the engine shut down, no smoke, no big bang. I had to call a Tow Truck which I never thought I'd have to do with this car. Got the car home and took a look at it this morning in the rain. This is what I found.


The timing belt is shredded, and when I attempt to turn the engine over the belt doesn't move, but there is still tension on the cams which leads me to believe it broke down by the crank. This is bad because normally the cams would all close and the valves would be saved, but in this case, the valves are all still open so this would leave room for the valves to collide with the pistons. Supposedly this is a Non-interference engine. But at TDC with the valves at full extension, there is only .010 clearance between both. I was reading online about other people who have had bent valves after a timing belt break.



Then there's a second issue that's got me even more concerned. I pulled all the spark plug wires and they were all normal except one. The rear bank, on the left hand side.... I pulled out and the plug wire itself was COATED in oil, it was dripping off. When I went to pull the plug, and i slid my socket down into the hole it slouched around in there before locking onto the spark plug. I can't figure out what would cause this. I am wondering if this is a pre-existing problem I never noticed or a result of the belt breaking (damage). I would like to do a compression test. How else can I check this motor over to make sure there is no valve or piston damage before pouring $500 worth of work into it? I need some creative ideas.

So, ya think i'm screwed?

Dan

[gsEnterpries]

what you do is hook up compessed air to each cylinder while all the valves are closed for that one. then let the air into the cylinder if hear air escaping either out the exhaust or intake you usually have a bent valve.

[Danspeed1]

When the belt is off the cams and the cams snap back... does that mean all the valves are closed?

How do I know if the valves in the particular cylinder I am testing are closed?

DG

[Sonyman]

IF it was me in that situation, i would break down the engine to the top of the block with the heads off. That way you can look and see everything yourself...provided you were mechanically inclinded to do that. I dont know if you are or not just saying. I had a similar situation late last year on my DOHC. The engine just stopped with no mechanical sounds, my timing belt broke because one of the front cams seized while the other cams and lower engine kept spinnin'. The problem was some RTV Sealant covered the main oil passage hole coming out of the top of the block blocking oil from getting to the top of the engine therefore seizing the cam. I managed to save my cams, used another engine gasket kit and got it running again. But with me, I have to know the deal with these engines, i chose to go straight to the core of the problem and fix or replace whatever on my back to the top.

[55trucker]

Going by what I see in the top photo. can't see it very well..the belt is still in intact, but the teeth on the timing belt have all sheered off so the belt still has tension but there's no way to drive the belt.

[Danspeed1]

This is going to be a stupid post but put yourself in my shoes if you can. The car has 204K miles on it and I have had it for 4 years (longer than any other car). Its beat, Its got damage all over it, but i drive it everywhere and I actually love the car. My girlfriend doesn't care for it so much and funds are tight right now. The transmission is shot. The car isn't worth $500. I would like to continue to use it until the transmission goes, in which case i can hopefully afford a cheap one. What's the easiest, most cost effective way to get her back on the road? Hopefully nothing did seize. I noticed a while back this belt was looking a little worn, but It's estimated to get 60-80K miles so I went against my better judgment and kept on driving (I will never make that mistake again); I am confident that the belt is the weak link. My only concern serious concern is the oil I found drenching the top of the spark plug (which I am hoping is a bad cam cover gasket), and that the pistons did not collide with the valves.

Unfortunately, your right, the best way to determine if there is any damage would be to tear down the engine, but that really doesn't make much sense on a car with 204K.

Keep it coming guys... Tomorrow I will tear the top end of the motor down (whats necessary to replace the belt) and I will take pictures! Hopefully I can get her going again.

P.S. I see there has been a few discoveries on the topic of cam timing. Are we still lining up the cam flats or is this an inaccurate method?

Dan

[no_doz]

dont be too concerned about the oil on the spark plug tops because thats just a bad cam cover gasket (the whole set is $130 at autozone for heads/intakes/etc... all of it) also i would just go ahead & start taking everything off & find out the engine is trashed, with the detailed instructions on this site (there is a picture guide on how to do everthing but take off the heads themselves & thats no major task)-chances are that something is damaged. honestly if you put it on craigslist with LUMINA Z34 ENGINE in the title you will be able to find someone to buy it for $4-500 within a week or 2 because people recognize that shit, and by that shit, i mean

Z34

recognize bitches.

[no_doz]

hahahaha when i asked the guy with the aurora engine to check the engine for compression to see if there was any damage or to take off the heads or else i wasnt willing to give him $300 for it (not when i have a good engine out in the garage & the head/intake gaskets alone are 450-650 bucks!)-let alone the fact that a new piston/pistons & valves would be very pricey on such an engine-& told him without any kind of proof that there is no engine damage i couldnt pay more than $200 for it-he flipped out & basically told me to go screw myself & that no matter what id pay he wouldnt take it & that im a jerk for even saying anything about the whole engine damage thing... because when i asked him if it was an interference engine or if it had suffered any engine damage he told me that it wasnt & that everything was ok (he didnt elaborate, he just kept telling me it was ok & asking whens the soonest i could come pick it up LOL). so i wrote him a long ass email telling him how shady that is for him to lie to people to sell them junk shit as quickly as possible before they realize how bad they messed up-hahahaha.

good stuff

[Danspeed1]

Day 1

Day 1

So I got up early this morning (before noon) and tore up the motor. I took pictures of the steps somewhat for my own reference but also in the hopes of helping somebody else out in the future.

So here goes....



Got the front timing chain cover off (I think I may have posted this picture already); as you can see the belt is all torn to hell, but still putting tension on the cams, holding them in place.



I took a look down the spark plug hole to see if they were all filled with oil. The other holes had a few drops but were not saturated like the rear left one.



I knew I was going to have to pull the power steering pump to make room for my hands to "properly" get into the timing belt area. So to avoid a mess I decided to pump the power steering fluid out of the reservoir ahead of time so it didn't spill everywhere.



God I am glad I did, this still was toasty... smelled horrible and burnt to a crisp!



Next I decided to get the overflow out of the way to make more space... and also the stabilizer



I removed the front cover, which is cracked like crazy and will either need to be replaced or repaired (more glue).

Can anybody see where the Major Failure occurred yet????


How about now (notice the bottom pulley)





More carnage for your viewing pleasure....





I decided not to even waste time with the belt, so I cut it off with a knife...

Take a long hard look, I couldn't believe my eyes... I've never seen teeth sheared off of a belt like this before. (this is a Quality Goodyear belt might I add)



So I had this great Idea that didn't work... THIS IS THE PART I AM HOPING SOMEBODY CAN INTERJECT SOME HELPFUL IDEAS.... I decided to pull the cam covers off and go cylinder, by cylinder pressure checking each one separately. To do this I would screw in the fitting to the spark plug area, and manually turn the cams so that the lobes were facing me, and not putting any tension on the valves. In theory I figured I would be able to pressurize the cylinders by turning the car over for about 5-10seconds, and if they didn't leak down I would know the valves are ok.

The first cylinder worked like a charm and I got somewhere between 90-100 as a reading.



The second cylinder also read about 95... (looking good !!! Thumbs up!!!)





The third cylinder didn't work out so well. I believe the pressure only made it to about 65, BUT THE CYLINDERS DID NOT LEAK DOWN WHICH IS A GOOD SIGN. Not sure why though it wouldn't pressurize the same as the first two.





To test the rear bank I would have to pull the intake manifold. To start the Air intake needed to come off....



All those sensors (EGR) and wires needed to be removed... I am not going to lie and tell you I know what everything in that mess did. If somebody would like to clarify what all those wires, sensors, and modules do that would be nice to know. What I do know (and this is the most important part) is that they all need to be hooked back up!



Why so much oil in the intake?????? Not making me feel great, but hey, shes got 204K on her! (yea I know, I'm drinking light beer... trying to stay on my diet,... sheesh!)



Alright everything is disconnected, so its intake time (this is the big one!)





Shes off!









Can anybody tell me what would cause the massive oil leak on the left rear cylinder....



I was completely missing an O-ring if you look. I really hope that didn't fall into the engine 30K miles ago. I will have to dig around and see if I can find it. Don't need any blockages causing oils starvation.


Ok now I am done for today, or at least this is all that i am doing. But here is the problem I ran into, hopefully somebody can help me. This caused panic for the first 20 minutes I was compression testing the rear bank. I didn't take a picture, but I hooked up the compression tester to the left rear bank, and I turned the lobes on the cam up towards me so the valves were in the fully closed position. I turned the car over for a good 10-15 seconds and it didn't build any pressure on the gauge. At first i was in a panic thinking that the valves were bent, and the motor was done. SO I decided to try the first bank (left) plug I had done earlier this morning, the one that read 90-100; after doing the same, what was once a 90-100 reading was now no reading at all. SO I tired the front bank, middle plug. And that one didn't have a reading either!!!! So I am thinking that either 1. The gauge from autozone crapped out, or 2. my method of checking for bent valves is flawed. PLEASE ADVISE!!!

Thanks for the help guys,

Dan

[jmgtp]

Things don't look so bad. I had it happen to me on belt with 10k on it. Shit happens sometimes.

The engine is supposed to be non interference but it has happened where there can be piston/valve contact.

I'd say clean all the belt shreddings out install a new belt and replace the idlers, tensioner pulley and tensioner actuator and see what happens.

The oil in the intake is probably a PCV issue. Mine always seemed to suck some oil into the manifolds, I use a catch can now and my manifolds stay nice and clean!

[GTP091]

when was the last time you inspected the belt before this happened??

[Z34_B]

I would ask myself, "Why did the belt sheer it's teeth off?" Take a look at all the pullies including the cams and make sure they turn. If you come across one that doesn't turn you should try and fix it. Maybe it's just a frozen idler. Rock auto has a kit for our cars, I just replaced my belt and all went well.

ACDELCO Part # TCK273 {4 Components (1 Belt, 1Tensioner, 2 Idlers) #19107099}
BELT KIT,TMG INTERFERENCE ENGINE APPLICATION; 2 DOORS

180$ smackers over at rock auto

[jmgtp]

That's good advice.

A failure like that deems it necessary replacement of all the timing components. It is good insurance to replace the bolts on the idlers/tensioner as well - not sure if they are included in the above mentioned kit.

[Danspeed1]

Thanks for the advice guys... I've heard those tips from a few others and I am going to take a good hard look at the belt line on the engine tomorrow.

I am still really torn on what to do. Again, I love this car but its got 200K on it and its beat. I could buy another one for $1500 or, I could save up a swap a new motor in. It's funny because I had a 1997 Pontiac Grand Prix GT that i absolutely hated. I attribute my hatred for that car to the awful sounding, low revving 3.8L engine (among other things). I really like winding this engine out to 7000RPM on the highway... it makes excellent power, sounds awesome and is a blast to drive. But i am also getting tired of the constant upkeep attributed with this engine. I am thinking this time (This is my plan so take note), I am going get her running one more time, see how many more miles i can put on this 3.4L and in the process, save a little here and there for an L67. I don't like the 3800 series, but I find it far superior in the abuse it can take, the power it is able to make (for cheap), and the ease of working on it. I think that's a good plan for right now.

I should have an update on this project in a couple of days... Napa tells me my Gates timing belt ($55) should be coming in on Wednesday!

Dan