Idle/ braking issues

[firemedicsafd]

88 k5 went thru frame off and now a dialy driver. Ran fine initially, develpoed a high idle thru all heat ranges. Braking would feel like the booster was bad. Brake light would come on anytime i hit the pedal. After it warmed up, i would tap brake pedal during movement and the light would go out...only to come back on when i wanted to stop. While trying to stop, the pedal would sometimes grab like normal but mostly like i had no booster on it at all. Sometimes, the motor would die. When i started it right back up, it would idle and run fine but the brake issue would remain under both conditions. Can anyone help me with this issue. During the frame-off resto, i turned a 79 block into an 88 motor by swapping in TBI and adding all the correct sensors to an 88 bodied blazer. Everything is hooked up as an 88 blazer. Thank you!

 

[BIOHZDK5]

I could be wrong but it could be either you need like you said a new booster, or a new master cylinder, or your vacuum to the booster is bad. But judging from you pumping the brakes and the light goes off, my experience has been a bad MC. Just my thought.

 

[firemedicsafd]

There is a small barrel looking thing in the flexible hose section between the booster and the intake port it gets its vacuum from. What is that? Can that go bad

 

[BIOHZDK5]

Yes, it is a vacuum filter. I good friend Murphy and his great law say it is possible for anything to go bad!!! I am assuming this is what you are talking about. Try to bupass it and see if it fixes the problem befor getting a replacement.

 

[firemedicsafd]

OK...MC replaced with minimal problems...brakes feel better although REALLY soft. But it stops even under panic stops. Idle is still high and erratic. Still getting a brake light in dash. Does that light also get reset when battery un-plugged? I also have a cooling issue i have a question about. During any operations, in the morning my truck will fire right up... warm up to about 260 deg, scaring the crap out of me, then drop back down to just below 210 and stay that way the rest of the day. I have dual electric fans wired direct, stainless steel rad and heater lines and a 195 deg thermostat. what is going wrong with that? It is only leaking a little coolant around the thermo neck but not enough to drop the level down. Any help on where to begin with that one would be appreiated since any delay would mean KABOOM! Thanks folks!

 

[BIOHZDK5]

The brake light sensor is usually on the brake proportioning valve and is triggered by thr brake line preasure so unhooking the batt. may or may not turn the light off. Try bumping the pedal hard and quick like a panic stop just with the truck in park and that may turn off the light. You may have an air pocket somewhere in the system so may not be a bad idea to bleed all four lines real good. Coolant issue I am still thinking on!

 

[firemedicsafd]

I fixed the brake issue...it was the e brake pedal sagging a little. Thanks though!

 

[BIOHZDK5]

Cool deal on your brakes. I talked over your coolant issues with a buddy of mine and we could only come up with a few possibilities.
1.Water pumo could be intermiten when could and once it waarms up it pumps normally.
2.Themastat is bad, sticking off and on.
3.Air pocket?? Of course this is not a known problem on a GM motor. Jeep yes, GM no.
Now these are all guesses so I dunno, I will be curious to know what the actual problem is.
Got me?? Keep me posted though.

 

[firemedicsafd]

you folks aint gonna believe this....i put the thermostat in upside down about 1.5 yrs ago when i built the motor. heat stays just below 200 all the time now...aint that crazy!

 

[BIOHZDK5]

Sounds like you had a friend helping you that day!! His name is Murphy and I hate his stupid law!!!!!! Wonder what the next Gremlin has got in store for you??

 

[firemedicsafd]

I know what you mean. This thing has been a SCHOOL of murphys law for the past 8 years! Now...since i got my brake and coolant thing solved, she idles HIGH for about the first hour, or when cold, then she idles really low to the point of killing the motor. The only code i got from this point was the ESC circuit( cant remember the actual code). But i read on here from 4x4high that just cleaning all the sensor connectors solves that issue. My ESC is new as are all the other sensors. I can check the IAC numbers but i dont know what they mean. Could anyone help me....AGAIN!? Thank you!