Truck won't run after intake gasket replacement

roden001 · April 12, 2005

Well, my buddy's having more engine problems.

His '97 Z-71 w/ a 350 has leaked coolant since he bought it several years ago. He was told by a mechanic that the intake gaskets needed replacing.

He finally got around to taking it in (been adding coolant for a few years), and as soon as they were done with the job, he got 5 minutes down the road and the truck went dead and wouldn't crank.

The mechanic has had the truck since then, trying to diagnose the problem. They have managed to get it to crank sometimes, but not run for very long.

They are now telling him that he has a problem with one of his rods, and that the fix will cost about $1,000.

He just called me with this latest news, and I'm a bit skeptical. It seems to be a huge coincidence that a warped (or whatever) rod would begin locking up the engine right after they did work on the intake. The truck has never done this until right after he started driving it when he got it back from the intake gasket replacement.

It seems to me that the problem is much more likely to be something related to the job they did--intake, fuel system, ignition, etc.

I'd hate for him to drop a thousand dollars and rebuild a motor that just needs something to be hooked back up correctly on the top-end of the engine. Can you guys offer any ideas? I have no experience with fuel-injected engines.

Thanks in advance.

Jon

Wingnut · April 12, 2005

I'd show up at that shop with a lawyer.

Or at least a very smart, very well dressed friend.

facn8me · April 12, 2005

Going several yrs adding coolant is not a good thing to do. My guess would be that due to 2 yrs of abuse by constantly running low on water as soon as the leak was fixed and the cooling system was finally allowed to pressurize the next weakest link after the abuse went, probably a head gasket. This resulted in the cylinder filling with water and hydro-locking the engine while bending a rod when the piston stopped. But this is just a guess.

roden001 · April 12, 2005

looks like I've got two different opinions here. Any additional input from you two fellas?

Or anyone else have a theory?

Thanks for the responses, guys.

Wingnut · April 12, 2005

facn8me is probably right.

Cooling systems are like that. Replace one part, and the rest of the system (used to less pressure/flow/volume) can't handle it. Replace the water pump, and the radiator starts leaking, replace the radiator, and the hoses start popping, etc. etc.

roden001 · April 12, 2005

Okay, well, here's another question, then:

What will he get for his $1000-$1200?

A rebuilt motor? Should he consider buying a short/long block?

facn8me · April 12, 2005

These are all just guesses without seeing the vehicle. An educated guess but still a guess. With out seeing the engine I have no idea what is bad or good. Could the engine be fixed with gaskets and a new rod? Possibly. Should that be all that is done? No. I would recomend either a salvage yard engine(toss up on what your getting) or a rebuilt. A shortblock is one way to go but you need to have the heads checked. With the heads being checked andd the added cost of swaping heads a long block may be cheaper. Just depends on how long he wants to keep the truck and how much he wants to spend. Don't forget the domino effect. Put a new water pump on it and new hoses. Check conditon of radiator also.

71GMC_3/4T · April 12, 2005

If they screwed up the intake installation and it got water in one of the cylinders and hydro-locked, then I think they'd be liable.

I would probably assume they've pulled the intake and found their mistake and hid it by now... Too bad for your friend.

Friz · April 12, 2005

If they screwed up the intake installation and it got water in one of the cylinders and hydro-locked, then I think they'd be liable.
I would probably assume they've pulled the intake and found their mistake and hid it by now... Too bad for your friend.

<{POST_SNAPBACK}>

That was my first guess.

Don't let a mechanic tell you that it won't happen, either. You cannot compress a liquid.

facn8me · April 13, 2005

If they screwed up the intake installation and it got water in one of the cylinders and hydro-locked, then I think they'd be liable.
I would probably assume they've pulled the intake and found their mistake and hid it by now... Too bad for your friend.

<{POST_SNAPBACK}>

That was my first guess.

Don't let a mechanic tell you that it won't happen, either. You cannot compress a liquid.

<{POST_SNAPBACK}>

I thought the same thing also. My only problem is the 2yrs of constant leaking. That's rough on an engine. Of course if it was a intake gasket the tell tale sign could be which rod it bent. It would be 1,2, 7 or 8 if it was an intake(usually) And yes you are at the mercy of the shop. I would want to know and see the failed gasket or whatever was wrong.

snoman · April 13, 2005

You cannot compress a liquid.

<{POST_SNAPBACK}>

Actually you can but it takes about 200,000 PSI to compress water 40% and the engine internals would giveway long, long before that.

etex211 · April 15, 2005

The four corner intake bolts (front and rear on each side) on the vortec heads may or may not go into water passages. Some do and some don't. Always seal these four bolts with some kind of thread sealant. I like to use the liquid copper coat on them.

Also, when using the stock vortec intake gaskets, the torque spec for the bolts is only 11 ft/lbs.

99-2door · April 19, 2005

You cannot compress a liquid.

<{POST_SNAPBACK}>

Actually you can but it takes about 200,000 PSI to compress water 40% and the engine internals would giveway long, long before that.

<{POST_SNAPBACK}>

Actually it takes 300,000 PSI to compress water and definately not 40%

mmmikkke · April 19, 2005

Going several yrs adding coolant is not a good thing to do. My guess would be that due to 2 yrs of abuse by constantly running low on water as soon as the leak was fixed and the cooling system was finally allowed to pressurize the next weakest link after the abuse went, probably a head gasket. This resulted in the cylinder filling with water and hydro-locking the engine while bending a rod when the piston stopped. But this is just a guess.

<{POST_SNAPBACK}>

...Or the intake manifold gasket was installed improperly and that let a cylinder fill with water and hydrolock, bending the rod.

But the problem occurred after 5 minutes of driving...So the cooling system had just gotten to max pressure. If there was no "shut off" of the engine, and if it died during a continuous 5 minutes out of the gate from the repair shop, the hydrolocking is unlikely. While the engine was running, if there was any coolant leaking into the combustion chamber, either from the head gasket or the intake manifold gasket, there would have been a lot of white smoke...a lot. Seems like your bud would have mentioned that.

So did the engine get shut off at minute-4 at 7-11 or something? And then it wouldn't crank? Or did the engine die while driving??

This would matter for the diagnosis.

roden001 · April 25, 2005

Thanks for the help, guys. Turns out his grandfather offered to buy a crate engine from GM. Had it put in and got his truck back yesterday.

Now there's a new problem: engine stalls and sometimes dies with hard accelleration. Only does this while in gear--revs up fine in neutral. Besides switching mechanics, any ideas about this new problem with a new engine?