Piston Slap??? '97 Vortec GMC 5.7L

[boatist]

Can you run an engine with the torque converter unbolted?? I read on some other sites that you can, but It would be nice if someone here has experience with that. Try to isolate engine from transmission. Just throwing out ideas. Best of luck!

 

[Gunar]

There may be a dong, dong, dong when the threaded Plates come on the Flexplate. This happens if the Converter moves a piece to the Flexplate. Can happen...

Gunar

 

[Will L.]

In theory you can. But if you TC slips foreward from the vibration it will break your flrexplate and maybe more.

 

[NVW]

You should be able to tie the TC back

 

[ak diesel driver]

IIRC the nuts are welded to the TC so even if it touched the flex plate it would be a smooth surface

 

[THEFERMANATOR]

You can unbolt the torque converter, but the pilot of it will still cause the converter to spin. The converter has a pilot stub that goes into the crank about a 1/2 inch, and if you undo the bolts, that pilotwill now be metal in metal spinning in the end of the crank. I don't reccomend it.

 

[6.2 turbo]

350 vortecs can have piston slap, and they always get quite after they warm up a little.

 

[OBE]

350 vortecs can have piston slap, and they always get quite after they warm up a little.

But did you read the post that said the piston slap was caused by a change not made until 1998? Mine is a '97.

 

[THEFERMANATOR]

I've never personnally seen a 5.7l vortec with piston slap. There were no real design changes in the 5.7l from 96 until the end if it's production for highway use in 04. The piston slappers were the ls style engines with the super short piston skirts.

 

[OBE]

I think mine is a lifter. One day I let it overheat. I found that another of the peculiarities, or common failures, is "burning coolant" that leaks into the combustion chamber from the intake manifold. The thing runs so damn good that it never gave any indication of overheating and it wasn't until I happened to look at the gauges that I saw it was pinned to HOT!

I got off the interstate as quickly as I could but I thought I'd "cooked" the damn thing! The next day, when I started it, that damn lifter was clattering like hell! I thought, oh well, it's shot now. Let me run it to see if it shuts-up. I did, and it quieted down. It went back to normal after some maintenance: an oil change and coolant fill up. I watched the reservoir carefully after that, and it was getting-rid of the coolant. I carried some jugs around with me. Then I added some "Barrs Leak" and it seems to have sealed it up. It hasn't used any coolant in a long while.

 

[THEFERMANATOR]

The early vortec's were known to have rod bearing failure and lifter problems because of the pos intake gaskets that leaked and would fill the oil with coolant. For a short while GM used federal mogul lifters, and they had issues with bleeding down, but the mellings ones didn't. Alot of the confusion about vortecs and piston slap is GM called the LS engines vortec's in the trucks, but they shared virtually nothing in common with the early vortec's. The LS engines started showing up in trucks in 98 for the 99 model year. But I've never seen or heard of piston slap issues out of a 4.3l, 5.0l, 5.7l, or 7.4l vortec's. The 4.8l, 5.3l, 6.0l, and 8.1l vortec's is a COMPLETELY different story. They ALL had piston slap problem's, it was just a matter of if the owner noticed it or not.

And stop leak is a HORRIBLE thing to add to any engine. Unless it's a vehicle you hate and feel like junking, I'd never add it. Stop leak is pretty well guranteed to ug up your cooling passages in your block, ruin your radiator, plug your heater core, and destroy your hoses.

 

[OBE]

The early vortec's were known to have rod bearing failure and lifter problems because of the pos intake gaskets that leaked and would fill the oil with coolant. For a short while GM used federal mogul lifters, and they had issues with bleeding down, but the mellings ones didn't. Alot of the confusion about vortecs and piston slap is GM called the LS engines vortec's in the trucks, but they shared virtually nothing in common with the early vortec's. The LS engines started showing up in trucks in 98 for the 99 model year. But I've never seen or heard of piston slap issues out of a 4.3l, 5.0l, 5.7l, or 7.4l vortec's. The 4.8l, 5.3l, 6.0l, and 8.1l vortec's is a COMPLETELY different story. They ALL had piston slap problem's, it was just a matter of if the owner noticed it or not.

And stop leak is a HORRIBLE thing to add to any engine. Unless it's a vehicle you hate and feel like junking, I'd never add it. Stop leak is pretty well guranteed to ug up your cooling passages in your block, ruin your radiator, plug your heater core, and destroy your hoses.

UH-OH!

 

[6.2 turbo]

The one I was thinking of is a 99 but still has the old sbc 350 vortec.

 

[OBE]

Now I have another problem. On cold mornings it runs real rough and I smell gas out the exhaust until it warms-up then it runs terrific, just like new. It's giving me a code for the MAF or MAP. I changed the Idle Air Control Valve because it was the cheaper of the two but nothing. I guess I'll have to go for the Mass Air Flow but it's $115.

 

[Will L.]

Have a can of maf sensor cleaner? Don't use anything else on it.

 

[OBE]

I did see a video about trying to clean one up. I guess I can get the cleaner at Advance A/P?

 

[Will L.]

Yes. I have had about 50% luck of it “fixing” it. It will only use 1/4 - 1/3 can to clean it.
If that doesn’t fix it and you need a new one, just use the balance of the can to clean the new one as preventative maintenance- clean it everytime you replace the air filter.

 

[THEFERMANATOR]

If the maf is in question, unplug it and see if it clears up. Those engines can run in maf or speed density as they have a maf sensor as well as a map sensor. And FYI, throwing parts at these based on codes is a great way to waste money. I hated the obd in the black box PCM's. They were the WORST for throwing erroneus codes. And we need to know the actual code AND the freeze frame data at the time the code is set. You may be throwi,g parts at a code that is telling you that you have a vacuum leak, plugged cat, low airflow who knows without knowing the code. Codes are diagnostic aides, NOT the psycic hotline telling you whats wrong. You take the code, find the symptoms, any assiciated problems, and diagnose the problem.

 

[Will L.]

So is buying cleaner if he doesn’t have any an error in the diagnostic flow chart? In fleets we always had a couple cans laying around, so it wasn’t like we had to charge a customer for one to do it.

 

[OBE]

Thanx to Will and Fermanator. I appreciate the advice. I read a good metaphor from one guy who described himself as "firing the parts cannon" at it!