Tapping felt through thermostat cover
04-20-2009, 11:56 PM
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Tapping felt through thermostat cover
This is a great, informative website you guys have. I'm glad I found you.
I've searched for similar threads to my "problem" with no exact match found. There's plenty written on ticking, tapping, clicking and knocking, but none of the threads that I've read mentioned the description of a VERY noticeable tapping felt registering through the thermostat housing, as in my truck. I have a 1990 extra cab, manual, w/3vze - 190,000.
It starts easy, runs great, just passed smog. It just has this light/moderate, ticking/tapping/knocking/diesel-sounding noise coming from the front of the engine. The noise can either be noticeable or not - usually is. It goes away (drowned out by engine roar I presume) at higher rpms. It almost sounds like something tapping against a shroud most of the time, therefore not a real "hard" tap. Although it does follow the rpms up and down with a rather sharp ticking. It's not really noticeable from the cab unless it's quiet out and at idle.
Again, the one difference in everything that I've read is that putting my finger on the Thermostat housing there is a steady beat to the tapping noise. I can also feel it, although less so, on the water hoses leading from the thermostat. I can barely feel it on the timing belt cover. There is no other place on the engine that I feel it, even immediately adjacent to those spots mentioned above. Everywhere else is smooth.
Not being much of an auto mechanic, I thought it might be a water pump sort of thing. I dropped the belts from the alternator and steering pump, thinking I could isolate the water pump, and started the truck for a couple seconds. The noise was still there and still registering through the same places.
Any thoughts?
Thanks.
I've searched for similar threads to my "problem" with no exact match found. There's plenty written on ticking, tapping, clicking and knocking, but none of the threads that I've read mentioned the description of a VERY noticeable tapping felt registering through the thermostat housing, as in my truck. I have a 1990 extra cab, manual, w/3vze - 190,000.
It starts easy, runs great, just passed smog. It just has this light/moderate, ticking/tapping/knocking/diesel-sounding noise coming from the front of the engine. The noise can either be noticeable or not - usually is. It goes away (drowned out by engine roar I presume) at higher rpms. It almost sounds like something tapping against a shroud most of the time, therefore not a real "hard" tap. Although it does follow the rpms up and down with a rather sharp ticking. It's not really noticeable from the cab unless it's quiet out and at idle.
Again, the one difference in everything that I've read is that putting my finger on the Thermostat housing there is a steady beat to the tapping noise. I can also feel it, although less so, on the water hoses leading from the thermostat. I can barely feel it on the timing belt cover. There is no other place on the engine that I feel it, even immediately adjacent to those spots mentioned above. Everywhere else is smooth.
Not being much of an auto mechanic, I thought it might be a water pump sort of thing. I dropped the belts from the alternator and steering pump, thinking I could isolate the water pump, and started the truck for a couple seconds. The noise was still there and still registering through the same places.
Any thoughts?
Thanks.
04-21-2009, 09:41 AM
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Ahh, so I didn't isolate anything with dropping the drive belts. I kinda thought that. Also I just discovered that I was wrong about the thermostat housing. The tapping noise is coming through the water outlet (top of the motor).
Timing belt, idlers, water pump, etc all appear to have been replaced about 60k ago.
Timing belt, idlers, water pump, etc all appear to have been replaced about 60k ago.
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