2001GMC Sonoma 4cyl 2.2 Both I and a co-worker with same. At only 89574 miles a his with less. These trks well maintane,and properly service. Have a crack block and or crack head,blowing exhaust and the water back out of the radiator.What with these eng

Submitted by desertdeeds Tue 06/15/2010

bad water pump, stuck

Submitted by jerryh20 on Tue, 06/15/2010 - 16:56.

bad water pump, stuck thermostat or overheating can cause this problem.not to mention running low on oil via a leak of some kind.

Most often this happens

Submitted by bfree on Sat, 06/19/2010 - 20:33.

Most often this happens because of a water leak which has gone undetected. I've seen water pumps on these trucks leak but didn't show until it was really in bad shape (too late because the engine ran hot).
visually check the water pump. There is a hole underneath the pump shaft (sometimes called the "weep" hole), if water has been leaking from there it will leave a stain (trail). This will give you an idea as to why it cracked the block, head or blew the head gasket.

Note--after the head is replaced/repaired, I recommend that you change the water pump and all radiator and heater hoses (regardless to condition) and have the system pressure tested, before putting the engine back into service.

I"m always on top of checking

Submitted by desertdeeds on Sat, 06/19/2010 - 21:54.

I"m always on top of checking water, oil,ect. The issue now is were may the crack be , in the head, block or head gaster. The exhaust is passing into the the water jackets,. somewheres. Enought to blow the water back out and exhaust gases with it.What may have caused it is too late for that.Just wanting to know where the crack may be. The oil is still oil ,no mixing of water,no oil in the water, no water coming out exhaust pipe.

the only way to find out for

Submitted by bfree on Sun, 06/20/2010 - 22:01.

the only way to find out for sure is to remove the cylinder head and gasket. Insepct the gasket and have the head checked for cracks by a machine shop. Next clean the block, and check for cracks there as well.
For the record, the head is more likely to crack than the block, it also warps from the heat (both conditions cause the same results/symptoms). Inspect the head gasket as well, sometimes the problem will show up there (the repair is still the same though).

In either case have the head shaved, after they check if for cracks and it's deemed usable.

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