Part 3: Troubleshooting overheating prob

Sep 22, 2007 8 Replies
J

UPDATE:



Well, I think we might be close to the problem. To refresh everyone's memory: the overheating (1995 Z28) came on suddenly. I did the following in an attempt to remedy the issue (listed in order of replacement):



  • Replaced thermostat with a Stant SuperStat heavy duty unit
  • Replaced radiator cap and flushed system, using Delco-spec antifreeze
  • Replaced water pump with brand new AC Delco unit

After these replacements, I would start the car and upon warm-up, the temp gauge would continue to climb into the red. As a reminder, this water pump is shaft-driven from a gear off in the timing cover. Look here:

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and here ...
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OK, fast forward to today. I took the thermostat housing off and removed the thermostat and had my son start the car up while I took a video. Watch here:
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Without stating what my opinion might be, I'd like to see what all the experts have to say.



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M

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Ouch. No pump action at all!

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's - Gone to the rust pile... Canadian Off Road Trips Photos: Non members can still view! Jan/06
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R

the only other thing i would do is replace radiator

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B

maybe check to see if the upper or lower rad hoses are not collapsed on the inside. check to see if the radiator is plugged. On any GM product I had when the heat guage goes over 3/8th of the way over that is normal. If it goes half way over it is over heating.

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S

The waterpump isn't turning.

Steve B.

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J

Thanks Steve and Mike !! I never considered that the pump would not be spinning, especially considering that it's shaft driven. When I told my son to crank the engine, I couldn't believe my eyes, so I asked him to do it a couple more times. So, basically, I'm getting zero circulation.

Obviously, the water pump drive gear is hosed. I'll be curious to find out why the shaft isnt spinning the water pump. I'll post back the results after the tear-down.

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S

Please do. You have my interest peaked on this one.

Steve B.

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J

I removed the front plate on the water pump, which reveals the water pump's impeller. This absolutely confirms that the pump/impeller isnt being turned by the engine:

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J

Hell all ...

Well, I've removed the water pump ... I can turn the water pump with the coupler attached to the water pump's splined shaft. However, the coupler will not slide and engage tightly to the splined driving shaft on the engine side, which of course means the splines are stripped. Here's the video version:

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