"Thank You Scott Schrader" for your response! We were wondering if it was possible that the mechanic was at fault or not. Nothing was said to my husband as he picked up our car about any other problems and told him they didn't find anything wrong! We needed alittle incouragement! Jeff is going to confront shop this morning, very upset and can't sleep at moment!
16 psi shouldn't be enough to do any real damage but would uncover a leak. I had a 3.1L on a used 1996 GP that had a separated head gasket. It was most prevalent once the engine ran for a while and the heat caused slight different expansion of the head from the block allowing some coolant to get sucked into the cylinders. Lucky my problem was found before catastrophic fail.
Hold on now.
There is no way that pressurizing the cooling system "wrong" is going to do anything more than blow hoses. If the headgasket failed after pressurizing the cooling system, then you had a problem to start with.
Pressurizing the cooling system is a time tested diagnosis and only harms the system if you already have a problem. More than likely, it started to dislodge a head gasket that was already failing and once the vehicle got up to operating temp, it finally failed.
Don't go blaming the mechanic until you are sure what you and anyone you are getting info from, know exactly what you are talkig about.
As Alcan pointed out, these engines have known cooling system problems and more than likely, is the cause of your problem, not pressure testing the cooling system.
Had a similar problem. This car has the 3800-II engine and 62K miles. Several gaskets (intake and plenum) failed and had $1800 in repairs. I believe these failures are related to post #4 (SEE link). You probably aren't using the red/orange Dex-cool coolant, so it may not apply, but more than likely, looking at a head gasket/intake gasket problem. Check for the coolant starting to discolor and accumulate sludge in the reserve tank, these are signs of trouble (not to mention sludge build up in the radiator) My car had a catostrophic failure one day where there was just too much coolant in the cylinders and car would barely run, blew out several sensors too. I don't think it's too common on the 3.8's, more so with the 3.4 and 3.1's. Gasket failures such as these, typically occuring at 40-60K miles are premature, yet GM at this time claims no defects or liability.
I'd just like to "Thank" everyone for your input. We have already begun to take apart the engine and replace the head gasket, then have mechanic check the internal parts. We Aren't for sure that it was the shops fault, nor putting all the blame on them, this is a subject we're not familiar with,and just wanted to get opinion of others. Others have told us you can over pressurize system, so had to do some research! It's a pain in the rear, but one that we are dealing with! Sincerely, Jeff & Pam
#11 of 12 shouldn't be able to overpressure system if checked right
Jan 08, 2003 (4:50 pm)
for instance, using the hand pump that screws onto the radiator cap's neck, you can't get that much past 18 or 20 pounds. anything you blow up with that tool was a dead part anyway, just hadn't fallen over yet to call your attention to it.
now, if somebody came back from welding class saying "looky what a neat tool I made here," and it happened to couple shop air to the cooling system, I would suspect 120 psi and up is likely to wreck the cooling system as surely as a sledgehammer.
technicians who know their subject instinctively avoid such gonzo approaches....
sorry you have a premature repair, 0patience said it way better than I was trying to say, it was already dead. I suspect you had reason to want the test done, and that reason was correct, the issue bugging you ended up being a big one.
The mechanic can't really fix it w/o a big repair bill. At the very least you are looking at a crankshaft turning/weld and a set of rod and crank bearings. If there was a true rod knock, there is a really good possibility of an out of spec rod end and to fix that the piston/rod assembly needs to be removed and re-sized. By that time a complete rebuild won't cost that much more... It's time to decide wether the car is worth that type of repair and go from there. It might be better to fix the car than it is to have a car payment. If you can't afford the repair, but like the car enough, you could re finance the car for the cost of the repair.