1991 Chevy Truck Water leak near front of oil pan

GEAUXTIGERS

MEMBER
1991 CHEVROLET TRUCK
6 CYL
2WD
AUTOMATIC
177,000 MILES

I recently changed the head gaskets on my 1991 Chevy C1500 pickup, 4.3L. The vehicle did overheat prior to changing it. I had noticed a loss of coolant in the days prior. Had heads checked and they were fine. Put everything back together. Went ahead and replaced the radiator since it was relatively inexpensive. New hoses, of course.

Cranked her up and she started to overheat again. Noticed that she was losing coolant again and found a steady stream of coolant leaking (or at least that's where it made its way to) just in front of the oil pan.
This is the first time I noticed this leak and I had looked before.

Any ideas? Freeze plug? Water pump?

I did not change the water pump since it seemed to be working fine but as I type this I am wondering if that was a mistake. I do not see water leaking from anywhere around the water pump though.

3 Replies

MHPAUTOS

MECHANIC
31,937 POSTS

Hi there,

Thank you for the donation,

A water pump would be high on the list, I would do a cooling system pressure test and using a torch and a mirror have a close inspection for this leak, we really need to positively identify where it is coming from, did you have the head checked over and re machined? And you did make sure that all the old gasket was removed, it must be spotless.

Mark (mhpautos)

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Monday, September 6th, 2010 AT 7:41 PM

GEAUXTIGERS

MEMBER
19 POSTS

Mark, thanks for the response

In response to your questions about the head - yes to all.

A little more details - after putting it together I had not done the valve lash properly and wasn't getting compression so with the help of another 2carpro, got that process completed. It started and sounded great. There were no obvious leaks at that time so I let it run, drove it around a bit and the temp seemed to be holding fine, but then after about an hr it started creeping up to 240 and towards 260 so I shut her down

Figured the timing was off a bit since I did it by hear, so went and bought a timing light. According to the marks, it was off - set it to 0 TDC. Ran it about 20 minutes and it creeped towards 240 so I shut it down again.

Flushed the system and decided to just go ahead and change the radiator, so did that. Pulled the water pump off and noticed that the gasket appeared broken on the water pump, so replaced it. After getting it all back together is when the obvious leak occurred. This leak was not there yesterday so it has to be me fooling with the water pump.

Figured I should replace that since it is inexpensive (about 25 bucks) but where the water was dripping from scared me from considering the obvious.

If it was the water pump wouldnt it leak straight down? I couldnt see it leaking from the actual pump, but it cant be a coincidence that the leak happened after I removed the back from the pump, right?

Thanks again, I know this is a long response on a holiday.

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Monday, September 6th, 2010 AT 8:48 PM

MHPAUTOS

MECHANIC
31,937 POSTS

No holiday here, I am in Australia.
I would be thinking that it will be the pump or a small bit of old gasket that you may have missed, this is all it takes for a leak to start, have a look at the pump, there should be a vent hole, if the seal is leaking it will be leaking at this point, I have been caught out with a small piece of gasket causing a leak, I am sure it will be something as simple as this.

Mark (mhpautos)

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Monday, September 6th, 2010 AT 9:01 PM