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God damn the DOHC Timing Belt


JoroCorona

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Alright. Blew the timing belt, less then 27,000 on it, but yeah. Doing an even 60 mph, and all of a sudden, no power. I heard no grinding or damaging sounding noises, but I'm preparing for the worst. The trans almost instantly neutraled out so I'm hoping it didn't kill any pistons or valves. I need a possible way to check for bent valves before taking the head off. Also, Am I better off just replacing the motor if the heads are fed up, or rebuilding it myself. Any quirks of the 3.4 that I should be aware of before pulling the valvetrain apart. Thanks.

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Wow... That really made my day. I thought for sure that it was an interference engine. Whew... Thank god... So... yeah... Timing belt is all I'll need. Wow... thats quite the load off of my mind. Suggestion of a good hi quality belt or just go for a gatorback?

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I'm thinking about doing all that and the intake gaskets cause I have a nasty vacuum leak thats f'ing up my idle bad. I makes it kinda hard to get in drive when it's cold too...

 

Trannys dont like getting dropped into drive at 1.5-2.5k rpms every morning

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I hope its not the case, and I know everyone says its not an interference engine, but its still possible that the valves are bent, its a matter of how much lash they have and how many miles are on the motor more than anything else. If you do end up having damage to the valves its going to be cheaper to get an engine from a yard than it is to repair it garunteed. In fact its also cheaper to plop in a used engine yourself in most cases than it is to pay to have the timing belt replaced.

 

I don't mean to be a downer, but hopefully you didn't do any major damage and you can get away with just changing the belt, I would however attempt to do a compression test on each cylinder to make sure though. I know its gonna be an absolute bitch to do since you'll have to turn the flywheel and cams by hand more or less, but it would be a hell of a lot better than going through the trouble of timing the engine correctly and replacing the belt only to find that your screwed anyways.

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If its a matter of how many miles are on the motor, then its a non issue. Its got about 77k. Everything in that motor should be barely worn. Its had proper oil changes and such and all maint done on time every time. I've even got the slips for it. Once I have the belt on, I'll do the compression test, but I'm pritty sure I'm good.

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With the valve covers off, you can spin the cams independly. Spin them around a couple of times. you will be able to tell if the valves are bent by watching the valvetrain movment.

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Its got about 77k. Everything in that motor should be barely worn.

 

You'd think so, but engines were built to die, driving it or not. Remember your car IS soon to be over 11 years old :oops:

 

You should be fine though...mine went too and I was cool :D

 

JUST MAKE SURE THEY CHANGE EVERYTHING

 

Belt, idlers, tensioner...you will be sorry if you dont

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I lost my T-belt at about 6k RPM's in my 91 Z-34 when it had 63k miles and everything was fine - so you should be alright. (but there's always that slight chance)

 

--Dave.

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this thread is one of the main reasons I'm scared sh*tless to buy a car with one of these engines...most of the Cutty verts I've looked at have this engine and I have yet to hear anyone ranting and raving about how great they are.

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I'd rant and rave about how nice it is...if that is I didn't have to remove the intake every time I wanted to do anything. Other than that, I love the engine. Stuff is going to need replacing on any ten year old engine, thats just part of the territory. So far I don't think I've done anything that isn't par for the coarse on any engine with 120k miles on it.

 

On the plus side this thing is WAY more fun to drive than a 3800. Sucks to a 5500 RPM redline, I like mine at 6500. It not only sounds badass, but its just more fun period. Now if I only had a five speed.

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I've heard the alternators go south pretty often because they are on the bottom of the engine and take all the road gunk...I realize the accessories have to be down there due to the wide heads but it cant be healthy for them...granted I've never worked on one of these engines but getting to a lot of these things sounds like a major pain...or the kind of thing where you just decide "screw the headaches, I'll pay someone else to do it"...I can remember the days when I had access to a lift and pneumatic tools...nothing seemed too difficult...but this crap of on your back in the driveway gets old real fast...I guess it helps tons tho when you know where the problem areas are and you can do a lot of preventative maintnence ahead of time...and I do have to go along with you on the engine music, I've heard a couple of these engines with CAI's and flowmasters and they sound downright nasty.

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definitely nasty as in "oh yeah baby!"...the kind of nasty that turns your head around in a parking lot so you can see what is making that sound thats tingling your insides...then he pulls into the street and romps on it and the hair on the back of your neck stands up as you say to yourself "Dammit, come back here and do that again!"

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Fuck Fuck Fuckity Fuck Fuck!

 

Alright, Got the belt on and all, timed it using the tools and shit...

 

Runs like ASS CRAP. Its got good compression, but the whole car vibrates at idle, and it hiccups at speed. I dunno what I could have possibly done wrong.

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I used the factory timing marks. Front bank timing marks are supposed to be inline pointing away from eachother and the the rear inline point twards eachother. The intermediate shafts mark should be pointing straight down which is where I think i might have made the mistake. It was kinda dark and I couldn't see the mark on the harmonic balancer that well, so I just eyeballed straight down on the intermediate shaft. Thats prolly where its off.

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