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Bad Engine Knock Before & After LIM & UIM Gasket Change

Z

Zachmi

New member
Hey Guys,
I've had my 2001 Grand Prix GT for almost 10 years, and with the exception of 2 transmissions, I've really had no issues with it until a week ago. Little by little I was losing antifreeze, and I thought it was just a loose fitting or something, then about a week ago, the engine vapor locked, and wouldn't restart, so I had to have it towed home. I let it sit overnight, and when I went out in the morning it started, just like it always had---except there was a noticible knock in the engine. Thinking it was just a knock from water being in the cylinders, I thought I would drive it in my driveway (fairly long, almost a quarter mile loop). The knocking quit after a minute, and it ran fine until it heated up. As soon as it was at operating temperature, it stalled again, but restarted, and I parked it. I removed the vanity cover off the engine, and could see coolant under the gaskets on my UIM & LIM, and went out and got the parts to fix both of them--It took a couple of days, but I took my time, and got it done.. I got everything hooked back up, and went to start it---It's still knocking--Loud--and the knock increases whenever I hit the gas. I'm thinking a bad lifter? Anybody have any ideas?.. How would I go about checking this out.. I obviously don't want to drive it anywhere knocking like this, is there any way for me to see what is going on with it myself?

Thanks!
 


How did your engine vapor lock? Being a fuel injected vehicle it would be very hard for it to do so. Did you change the oil after the lim job? Did you put a new uim on it?
 
Dsmuts, I assumed it vapor locked, the engine shut down, wouldn't crank at all---And from what I read on here, and other sites, I just gathered that it was the cause of my issue. I changed the oil, and the coolant after the gasket replacement, and ran a gallon of cheap oil through it before I put valvoline back into it. I didn't replace the UIM, it wasn't cracked or anything, I just did the gaskets.
 
When I took it off to replace the gaskets, I checked it pretty good, and didn't see any cracks anywhere. Would that be causing the knock if I possibly overlooked it?
 
It could. But what has actually caused the knock most likely is the ingesting of the coolant and subsequent hydrolock. More than likely it spun a bearing and you will be looking for a used longblock.

Search you tube for 3800 rod knock and see if that sounds like what you have going on.
 


Fordman77,

Would that be something that would be worth doing?--if so, what would the cost be/how long would it take if I could do it myself? Or would you just replace it with a used engine?
 
When I changed it after the gasket installs, the old oils was fairly dirty, but no metal, or coolant that I saw.
 
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