dualblade

ok so when i bought my car one of the hoses going into the firewall was blocked off, therefore my car has no heat. i'm guessing this is because of a leaking heater core but i want to make sure before i proceed with taking apart the dash. i'm pretty sure it's the intake hose that's blocked off because it would basically make no sense the other way. when looking at the two cooling hoses that come out of the firewall, it's the top one that is cut and blocked off. the bottom one is, from what i understand, the return line and it is still in place. the return goes into a metal tube thing that runs horizontal a few inches above the exhaust manifold. it then comes out of this tube and goes into the heater control valve, then back into the waterpump. i have to admit this doesn't make much sense to me so maybe someone could explain why it's set up like this. i guess i just imagined that the heater control valve would be placed between the engine and the intake hose that leads to the heater core.

anyway the real question/problem is that i seem to have a blockage somewhere in the hoses inside the car. are there any valves or otherwise that would block the flow of water/air inside the car?

ok i think i'll explain my troubleshooting procedure so this question makes more sense. i took the return hose off of the metal tube thing and took the cap off of the intake hose so both of them are open now. what i figured i'd do was pump water through the intake hose and see what came out the return. i know i could have just bought new hoses and reconnected to see what would happen but i figured that if the heater core does leak, coolant would make a big sticky mess inside the car but water would pretty much dry up and cause no real damage (i have the battery unplugged so i wouldn't have to worry about the water shorting out stuff).

well i've got a piece of cut off garden hose in my garage (only the female end remains. the cut off end i stuck inside the water intake hose and put a hose clamp on that. the other end i figured i'd screw onto my hose outside and just turn on the water. if i saw it leaking inside the car i'd just turn off the faucet. the now exposed return hose has a funnel right under it which drops water into a bucket under the car so i don't make a big mess. of course, the weather decides to get all freezy on me today so instead of the nice warm spring day i wanted we got snow. can't run the water through the hose outside cause it might freeze in there and cause all kinds of trouble. still wanted to do something though so i put my mouth up to the end of the hose and blew into it to see if i was getting air through (yes this was pretty gross). put alot of pressure into the hose (well, as much as my cheeks could take) but nothing came out the return.

now i'm pretty sure that the previous owner had put some stop leak stuff into the coolant which was leaking from the waterpump when i got the car. i've since done a t-belt/pump job so that's been fixed but is it possible that the stop leak stuff has blocked up the heater core? if this is the case is there something i can do to fix this situation? can i pour drain cleaner in or some other substance or do i have to rip apart the dash and take out the part that's blocked up? also, am i just missing something and there's an obvious reason why air/water wouldn't go in the intake and out the return? and finally, is the placement of the heater control valve correct or has that been messed with (presently right near the top of the oil filter)?

whew, that was quite the mouthful
for any of you with incredible attention spans that actually finished all that, i appreciate any help you can give me

dualblade

bump for morning crew cause i could really use some advice

Dal Heger

Sorry no idea. The heater core should not be blocked, if you can't flow water through it then it's toast. I've heard (although I haven't done this yet - knock on wood) that you can replace the heater core by taking off the glove box and some stuff under the dash. The factory manuals basically say to remove the dash to get to the heater core.

I wouldn't use any chemicals in the cooling system to try and unblock the core. If any of those chemicals get into the engine coolant then it could be disastrous for the aluminum head and block.

Yes, your heater control valve is in the correct place. It was moved in the later cars to prevent coolant from soaking the clutch if it failed. Its also a lot easier to get to in this location!

Good luck!

Dal.

Flight_951

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by dualblade:
<strong>bump for morning crew cause i could really use some advice</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">This is a wild guess but shouldn't the heater be in the "on" position for coolant to be able to go through the core? Can you idle the car and put the heater on full blast? HTH

Dal Heger

No, the heater core should flow freely with the hoses off (which is what he's testing out).

While it is true that the heater control valve will stop the flow of coolant into the heater core, dualblade has the heater hoses off and testing the flow through the heater core itself. There should be no blockage in the actual heater core.

Hope that helps.

Dal.

dualblade

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Dal Heger:
<strong>Sorry no idea. The heater core should not be blocked, if you can't flow water through it then it's toast. I've heard (although I haven't done this yet - knock on wood) that you can replace the heater core by taking off the glove box and some stuff under the dash. The factory manuals basically say to remove the dash to get to the heater core.

I wouldn't use any chemicals in the cooling system to try and unblock the core. If any of those chemicals get into the engine coolant then it could be disastrous for the aluminum head and block.

Yes, your heater control valve is in the correct place. It was moved in the later cars to prevent coolant from soaking the clutch if it failed. Its also a lot easier to get to in this location!

Good luck!

Dal.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">thanks alot for the advice. i'm gonna take out the glove box and see if that gets me anywhere. hopefully it'll work out cause i'm really really not looking forward to taking out the dash

Dal Heger

Good luck. It'll be really tight, but I've heard that people have had success. Let us know what you find.

Dal.

Bri Bro

Since you are going to remove it anyway, try pushing a wire down the tube. If the stop-leak plugged your heater core, I wonder what it did inside the rest of the engine.

dualblade

update: ok so good news so far.

went out there today and decided to try again with clearing up the blockage. figured if i had to replace the hoses and core anyways i might as well try. had some pretty stiff vaccuum hose that would do the job i wanted to so i stuck it into the intake fitting on the firewall and blew in. nothing. decided to try the opposite so i stuck it in the return fitting and blew in. this time i had much more success. a bunch of coolant/crap came belching out of the hole which obviously made me pretty happy. i guess whatever was blocking it up was closer to the intake. i couldn't push it through the heater core blowing into that but blowing through the return cleaned things up.

went ahead with my previous plan of hooking up a garden hose the the intake hose and seeing if water would now come out the return. turned it on slow at first and coolant started coming out the return. then i gave it full blast power and a steady stream of coolant/water came out till i had emptied out the whole heater core and it was just water coming out now. took a look under the dash to check for leaking or any evidence of anything wet. left the water of for about 5 minutes of full power and didn't see a drip.

pretty happy at this point, so i went out the get a hose so i could connect the intake fitting to the block and make the system whole again. i will update again tomorrow cause i haven't turned the car on yet to check if i have heat. i removed the exhaust to give me much more room to work (just the exhaust manifold is still in place) and it's too loud to run it at night for enough time to let the car warm up. broke two bolts taking the downpipe off the headers so i have to get them replaced before i put the exhaust back together. have to admit, the sound of open headers is pretty freakin cool. had never heard my car without the exhaust before; now i know my car's definately got a pair

Dal Heger

Yup, these cars are fantastic for waking everyone up when they rumble by. 750cc of displacement per cyl will do that!

Good luck, I woulnd't be surprised if when the system gets pressurized that you'll find a heater core leak. Just be prepared for it.

You can go to autozone and borrow a pressure tester. Fill the cooling system up and pressurize it to 15 psi. Let it sit. See if it hold pressure for 5 - 10 minutes. If not, you have a leak.

good luck!

Dal.