1G Possible head damage?

[Perkul8r]

Well, here is my story, I picked up a 1990 laser with the 4g63T from a guy who said the timing belt went out on it. So i was thinking bad valves right away. So i tear into the car today, and i get to the timing belt and the belt is still there. All nice and tight except, there are teeth missing off it right around the crank gear. The owner said the motor would turn over freely and never sounded like it had it anything, but the cams wouldn't move. So he had a compression check done and it was zero. I'm thinking cause mainly the cams wouldn't turn. So i pull the plugs and as far as i can see there isn't any for sure signs that the head was hit. I am trying to find a bore scope to see for sure. The car was not under boost when this happened he was just coasting.

Do you guys think that it is possible that the teeth stripped off at the right time with the valves closed and that the motor might be good? Is there anything else i can look for that would tell me yes or no on bent valves?

Thanks.

 

[steve]

Expect that they're bent.

You can pull the rocker cover off and check each valve to see if the rocker is still on the cam and valve stem, that none of the valves are hanging lower than they should be but short of pulling the head off you may not see the damage.

 

[Perkul8r]

I'll check that, I am hoping for that by some sort of act of god they aren't but thats never usually the case. Thanks,

 

[rx7ttlm]

its unlikely your valves went un punished..

 

[Perkul8r]

Ya, i just went out and pulled the VC off and sure enough, all but one of the rockers for the exhaust valves are off. So yep. Head damage. Dam. Looks like its time to sell my lil pickup and get some new parts.

 

[jdodds]

Pull the head off. Theres a chance you can still use it with some minor machine work. Youre definitley gonna need some valves, guides, possibly mill the head, and probably new pistons depending on the RPMs the engine was seeing at time of failure. Im going through the same thing right now and its not quite as expensive as most would think if you can do the work yourself.

 

[Perkul8r]

well, i can do most the work myself except the machine work. And the PO said he was just coasting when it happened so i aint sure about the pistons. But if i had to put new pistons in i would just find a cyclone engine and swap it. Which is what i am kinda looking at doing.

 

[steve]

It's really unusual for the pistons to get more than a slight dent but common for the valves to bend and often crack the valve guides.

 

[Perkul8r]

I may just find a new head. I kinda want to get the car running soon. I know these things can be picky but i love the car.

 

[jdodds]

FYI, the cyclone engine is exactly the same as a normal 4g63. The only difference is a junk manifold that flows like 3cfm more than a stock 1g. If you really want one, hit up all the utah people and Im sure you could find a cyclone manifold that someone would just give to you.

In short; Cyclone engine = hype x (money + fire)

 

[Perkul8r]

Well, i got the head off and its not good. Which i figured already.

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But here is my question. I can definitely see where the valves impacted the pistons. Now, i really don't have the time to rebuild a shortblock. Is it ok to clean this up, make sure nothing is gonna come off, and run them for the time being.

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[romeen]

But here is my question. I can definitely see where the valves impacted the pistons. Now, i really don't have the time to rebuild a shortblock. Is it ok to clean this up, make sure nothing is gonna come off, and run them for the time being.

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I think you might be ok for the time being if you grind down the sharp edges of those dents. But also keep in mind that the ring lands may have been damaged as well.

FYI, the cyclone engine is exactly the same as a normal 4g63. The only difference is a junk manifold that flows like 3cfm more than a stock 1g. If you really want one, hit up all the utah people and Im sure you could find a cyclone manifold that someone would just give to you.

In short; Cyclone engine = hype x (money + fire)

Not to get off topic but every person who has posted their impressions of the Cyclone IM WHEN IT HAS BEEN PROPERLY SET UP TO WORK THE WAY THAT MITSUBISHI INTENDED IT TO has had nothing but good things to say about it. I have yet to come across a post knocking it when it's been set up the correct way.

 

[Perkul8r]

I guess i am gonna hope for the best. clean it up, but the new head on and do a compression check when done, and hopefully all goes well till i can rebuild the motor. Thanks for the info.

 

[XiKeiyaZI]

Just a short story.

I had the same thing happen on my N/T. The teeth ripped off at the crank... my CAMs stopped turning with the dowels up. All valves were damned close to closed. I pulled everything and checked.. not a single impacted Valve. Not a dimple.. nothing. I got LUCKY.

So for reference.. it IS possible to escape a timing belt slip with no damage... though I would assume that's a VERY rare occurance.

 

[Perkul8r]

So i got another car and took the head off. and well, sadly i have another problem. There are two valves that had slapped the piston. Not very hard, but they did. The one looks like it seals good, the other one seals about 3/4 all the way around. But i can see a little gap on one side. So I was thinking i could just replace those two valves. But here is my other thing. The car is a 91 talon TSI. but the pistons are all marked 63D, so i am thinking this is an NA motor. If so, can i just swap my turbo cams into the head and go? Thanks.