strange issue

[RunUoveR]

well a few weeks ago i blew the seal out of the waterpump and replaced the pump and tstat. it didnt leak any and the rad is still full but sometimes when im sitting at a light for a while the heat starts blowing cold and its not untill i get moving it blows hot again, Air bubble im guessing?

2nd issue is when i go out to the car and start it and let it sit and warm up i can hear the RPM pulsate up and down for about 20 sec then i guess the motor gets warm and the idle drops down to normal speed and stays steady. if it was a vac leak usually id expect the pulsation to stay but then again im used to carbs so idk...

and the 3rd issue is sometimes very rarely when im on the gas moderatly hard the engine light flicks on for a sec and back off again before it shifts right around 45mph, i guess into OD?

well thats about. car's 100% stock.

thanks

[gadget73]

1) sounds like an air bubble

2) could be a leak, could be a dirty IAC. Try removing the IAC and cleaning it out with carb cleaner.

3) which engine light, the red one or the yellow one? Red means overheating or no oil pressure, yellow is computer related. If its the red light of doom, you'll need to figure out whether its hot or has no pressure. If its the yellow one, scan it for codes and hope it tells you something. If nothing, there are a lot of things that can randomly trip that light, many of them egr or egr vacuum system related. Last time I had one randomly pop on like that it was a leaky egr valve.

[RunUoveR]

yes, it was the yellow one

i did get the red one when the water pump leaked out on me before i changed it lol

whats IAC stand for? i guess i have a little more investigating to do. thanks for the heads up

[gadget73]

idle air control, its the tube shaped thing on the back side of the throttle body. One plug, two bolts and it comes off.

[89merk]

i had that happen to my car with the yellow light flickering, it happened to be the main wire harness...had a short circuit

[RunUoveR]

my friend mentioned that he thinks there might be a clog or a "choke point" in the heater core and only at high rpms is there enough flow to keep it full of warm coolent

sound logical to anyone else?

[gadget73]

Possible. Unhook it and use a garden hose to flush it backwards. If a bunch of crap comes out, you'll know what the problem was. If a bunch of crap comes out, I'd actually strongly suggest flushing the whole cooling system. They tend to get real neglected in these cars. I flushed mine probably a dozen times over the course of 2 years, and up to the point that I rebuilt the engine a second time and replaced the radiator again I was still getting garbage from the original nasty cooling system.