| Author |
Message |
David J. Silva (Cypress) (63.188.49.114)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 23, 2003 - 6:35 pm: | |
Forgive this off topic question but I know this to be a reliable group of backyard engineers(and a few real engineers) and I am at the end of my patience and it's very cold here.
1997 Chevy Astro 4.3L
replaced a bad water pump and the heater stopped working.
there are two extra water lines from the water pump, one is a jumper to the front of the intake maifold and the other is presumably the heater supply line. The heater return goes to the rear of the engine (right?)
None of these lines puts out water with sufficient volume to warm the heater core
I ruled out a clogged core by running hot tap water in to the core. Went in hot, came out lukewarm and hot air came out of the vents.
Older models (like my 89) supply the heater from the lower radiator line with no extra tubes from the water pump.
If i can't figure out what i am doing wrong I may get an older water pump and retro this system but my wife doesn't like me to re-engineer cars that are not paid for. |
Geoff (Geoff) (64.1.0.32)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 23, 2003 - 8:16 pm: | |
You need to figure out which hose is coming from the heater as the return line and loosen the clamp (don't disconnect the hose) where you can and bleed the air out-- it sounds like you have an air lock, which is common when you take the cooling system apart.
--Geoff
'82 RTS CA |
Jayjay (205.188.209.11)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 23, 2003 - 8:35 pm: | |
Might have been sold the wrong gasket, and part (or all) of one of the ports is covered by it. ...JJ |
smoky (12.222.48.5)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 23, 2003 - 9:07 pm: | |
many times you can solve problems like this with a little detective work Geoff is right on with his air lock scenario and I see this alot especialy if astro is equipted with rear heat however I would suggest checking that water pump is moving the water the right direction before the days of continueous serpintines belts all water pumps turned clockwise but now some turn counter clockwise depending on belt routing. also make sure that belt is routed properly so what I'm tring to say is that you may have the wrong water pump
Lots of luck, Smoky |
Henry R. Bergman, Jr. (Henryofcj) (65.194.145.59)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 23, 2003 - 9:19 pm: | |
Do you have standard old style drive belts or the new fangled single surpentine single clogged drive belt that runs everything?
Soossss many different water pumps were made for the small block V8 which essentially you have only 2 holes less with your 262 bowtie V6.
Does the car overheat with the new pump? Is it a new pump or a rebuilt one? Believe it or not, some pumps turn the opposite direction and the vanes are slanted in the opposite direction.
Do you have the proper replacement pump? Bet there are over 50 possiblities. A little detective work may find you got/received a wrong one.
Happens all the time. You would be amazed at what can happen when computers get the wrong data when they are programed with supposingly compatable replacement parts. Good luck. |
David J. Silva (Cypress) (63.188.49.114)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 23, 2003 - 9:31 pm: | |
followup, additional info
the cooling system seems to work perfectly. for a while it would not rise much above 120 deg,
found a bad thermostat, replaced, and it rises to 190 deg. and stays there no matter what.
Given that this engine/cooling system has been very forgiving (low coolant etc) is it possible that it could still move enough water to keep the engine cool but not move water sufficiently for heating? i.e. bad pump, wrong direction impeller etc.? |
David J. Silva (Cypress) (63.188.49.114)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 23, 2003 - 9:47 pm: | |
but wait, there's more...
the wrong direction impeller theory is starting to get under my skin, please verify my assumptions:
water flows out the fron of the engine, into the waterpump, down to the lower right hand side of the radiator, out the top laft side of the radiator where it passes the thermostat. Correct?
At one point in my aimless trouble-shootng i noticed pretty good water flow from what i thought was the heater return line coming from the rear of the engine block.
thanx very much for your help so far |
RJ Long (24.127.74.29)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 23, 2003 - 10:35 pm: | |
David -
Unless you're Astro's weird, the water flow path you're describing is reversed.
Most engines have the hot water flowing out of the thermostat into the top of the radiator, out the bottom of the radiator into the water pump, where it's pumped to the top of the engine and the cycle repeats itself.
The heater usually (but not always) picks up it's supply off one of the heads and either returns it to the system just ahead of the thermostat, or sometimes just ahead of the water pump (after all, the heater core is really nothing more than a small radiator, so it cools the water down). Some systems pick up the hot water for the heater just ahead of the thermostat, taking advantage of the heat off both heads, and then return it around the water pump.
Dunno, but maybe you've got your heater plumbing backwards?? Or maybe a jaunt to a local used car lot w/ a camera to take a pic of another Astro's plumbing might help. . .
HTH,
RJ
PD4106-2784
Fresno CA |
David J. Silva (Cypress) (63.188.72.196)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 24, 2003 - 8:48 am: | |
It Works!
Thank you all very much. I am not sure exactly what did it. Bleeding the air off seems to have done the trick. The heat worked well enough before for the normal climate here (North Carolina) but the record cold was too much.
One more question, the car has rear heat but right after I bought it the belt tensioner came off and busted through the heater bypass valve. Given the climate here I decided to not replace the $90 valve and I just cut the rear heat out.
Now I'd like to revisit that. Can someone tell me what the heater bypass valve does?
It has a total of six connections to it and a vacuum controled valve.
Thanx again
(Before I posted here I tried a Chevy truck board and an Astro board, all i got were answers dumber than my questions) |