Flex plate?

[Draq]

OK guys, so my '87 'burb 454 had a metallic hollow knock/bang one day. Got under it and am 85% sure it was coming from the bell housing, which strongly suggests flex plate. Well driving to work a day or two later (literally about 5miles away) there's a metal breaking sound, and the engine goes from purring, to reminding me of the truck from Beverly hillbillies. I pull over, hop out, and while its still running, look underneath. It was running really rough, and had puked a bit of oil from somewhere(still not sure from where, but it wasn't much, dipstick still says full). So I hopped in and shut it off. This is the second engine its had since I bought it. The first just shut off going down the highway and would never do anything ever again. My mechanic at the time didn't diagnose it, just swapped engines with one I found on eBay ($900) both engines had about 70k miles, the truck is clean and in great shape (except for some paint fading on one side, I'm guessing from sitting under a carport for ever). Now I'm not David frieburger, but I'm also not a total newbie either. But its really weird and incredibly frustrating. Now here in a few weeks the funds will become available to me to get it fixed, but I don't want to have it turn around and break again. I did recently go try and start it. Really slow weak turn over(like if your battery isnt charged) but it did eventually start. Still ran rough, still had same noise, shut it right off.

 

[mistaake]

what does your oil pressure gauge say?

 

[Draq]

what does your oil pressure gauge say?

My gauges have been normal from what I remember. Except my temp gauge wasn't working after the engine swap, but checking my radiator often yeilded a full level.

 

[1987 GMC Jimmy]

If you suspect a flex plate issue, you should remove the cover inspect your flexplate for cracks. Broken teeth wouldn't cause that, but cracks might. Oil pressure issues make a lot of sense, though.

 

[lessersivad]

Yup, pull the inspection cover and check the flexplate.

To really check it you MAY need to slide the transmission back, along with the torque converter.

You shouldn't have to remove the transmission entirely. Simply get a couple of longer bolts (3" to 4") and replace 1 bolt on each side of the bellhousing.

unbolt the driveshaft and either remove it, or suspend it with bungee cords (if you don't want to lose any ATF.)

Unbolt the torque converter from the flexplate and push the converter back towards the trans.

Then remove the remaining bolts and slide the transmission back on the longer bolts (they act like long alignment pins).

You should be able to see if there are any cracks between or around the flexplate mounting bolts.

If cracks or other damage to the flexplate is detected , remove and replace the flexplate without removing the trans. using the clearance you have by sliding the trans back.

I've used this method a couple of times on different vehicles.

Hope this helps.

 

[Draq]

Thanx guys. So that does sound like what's wrong with it? I really want to put all this crap behind me and get back to having my own running truck.

 

[lessersivad]

Well Draq, all I know is the last one I did almost sounded like an intermittent rod knock.

The only way you'll know for sure if it's the flexplate or not, is to inspect it.

Rather hard to diagnose over the interwebs.

 

[Draq]

Well Draq, all I know is the last one I did almost sounded like an intermittent rod knock.

The only way you'll know for sure if it's the flexplate or not, is to inspect it.

Rather hard to diagnose over the interwebs.

...sigh... I know. Thanx gents. I'll keep y'all updated.

 

[Draq]

OK its in the shop. I should get a call Monday afternoon.

 

[Draq]

So he said its acting like the motor is seizing. He said he'll investigate more tomorrow, they've been backed up with the summer rush. It could be a dented oil pan, but he said he'll pull the torque converter and flexplate and that should tell us a lot.

 

[Draq]

So its totally screwed. Apparently its about to throw a rod. So its officially for sale.

 

[1987 GMC Jimmy]

Okay. Forget the whole spiel about the other engine. I reread the first post, and I'm sorry that this engine didn't work out. I can't get rid of anything, but if you're fed up with dealing with this particular vehicle, I totally understand. You might be able to get a short block from a reputable source, use your top end, and put it all back together for not too much. Scrap the short block that you have in it now and just play it cheaply. You may come out okay. Just food for thought, bud.

 

[Draq]

Thanx. I was really upset. I might do that. I really do love this truck. Appreciate the help gents

 

[Draq]

My wife can't decide what to do, seeing as its actually her truck AND her money. We could fix it again (putting a third engine in this thing, and way more money than we paid for it.) Or buy some other used vehicle, that may or may not also crap out in a few months.

 

[1987 GMC Jimmy]

I've been looking at Craigslist for you. I don't know how far you're willing to go, but I found a '98 Chevy with a 454 that's getting parted out in Dallas, and I found a 454 in Kilgore that was more attention grabbing. If you were willing to get that one, you could sell the lesser set of heads, the intake, valve covers, etc. and get most or all of your money back. Maybe not even that particular one, but that's the way to come out cheaply on this. You could also venture into building it and/or installing it yourself if you have the time. Big money saver right there.