Barrier

This morning I went for a drive, everything fine. 35 degrees out. Accelerated hard from a stop and suddenly inside of windshield fogged up and I smelled anti-freeze. Stopped, turned defroster on searched for leak on passenger side inside, nothing. Looked under hood nothing, level of coolant seemed fine. A little fluid around expansion tank.
Cleaned windows, and drove home. I noticed that the temperature varied from 180,2,3,4,-190-185,8,9(where it normally stays at 185 and rarely varies at highway speed) 200 back to 183 188 etc.When stopped and idling went to 228 and fan kicked on went down to 190 etc. Got home put some GM spec pepper pellets in the radiator thinking slow leak, might help til I could replace core.
Went for test ride to disperse the pepper pellets as per instructions, drove fine. Nailed it again and same problem, windows fog, smell antifreeze. Again I figured heater core. Only problem is no leaks inside and when the defroster or heater is put on high it actually starts to clear winshield. ??? Now I'm starting to think a sticking thermostat ( temperature fluctuations). But why antifreeze smell inside and fogged windows?? I have always seen inside fluid coming from heater box and further fogging when core goes and it happens whenever engine runs not just when accelerated hard??
Could antifreeze be coming in from vent at windshield base? Just small amount near overflow??
I am stumped. I don't want to pull the core if I can help it, particularly if it's not the problem. :confused: :confused: :confused: Barrier

greenvette95

On the pass side go up with your hand into the main kick panel and feel around for any wet spots, I had the same problem you had and the heater core let go, it was a small leak, hard to find. Good luck. :D

GlockLT4

Sounds like the heater core to me ... lots of people will say to do yourself a favor and pay the dealer the $800 or something it costs to have fixed. When mine goes out, I am going to tackle it on my own, since the part is about $30-40, and labor is over $700. The only way I afford to keep this vehicle is by doing as much of my own work as possible on it.

If you don't need your heater, just plug up the heater line going into the heater core. If you are going to tackle this on your own, GET A SERVICE MANUAL!

Barrier

Thanks for the reply. I have the manual and it doesn't look like a gazillion hours, but it's hard to tell. The instrument pad actually looks easy to do, rest seems to be straight forward.
Anybody on the forum actually done a heater core replacement on an '84-'89 with manual AC?
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vanduker

Hate to say it, but with the temperature fluctuations you describe, I'd suspect a head gasket. It may be that the heater core has failed as a result of the combustion pressure into the cooling system. I've changed the heater core in an 84 (result of a failed headgasket) and it was difficult. The manual shows removing the majority of the dash (instrument panel and such) but we did it with most of the dash in place.

You might borrow a radiator pressure tester and check the system after changing the heater core and make sure you do not have a failed headgasket.

Mark

TreyZ28

hey if u need a heater core, email me with an offer
i got one that doesn't leak and its collecting dust...
Tetnies@optonline.net

cohocarl

If I remember right, it took me about a week of evenings after work to do mine. (in a 20 degree (F) garage) No it's not brain surgery, but it is a P.I.A. :yesnod:
I apologize to TreyZ28 if I hurt a sale, but if the core is used, I wouldn't use it. I'd go with a new one. I'd hate to re-do mine any sooner than I'd have to.

Good luck,

Carl

Grzldvt

If you do a search in the C4 Archives for "Heater Core" You will come up with a bunch of us that have done it..
As said before it's not brain surgery, but it can by trying. If I recall all the bolts were 7mm. Go out and buy the best darn socket you can, spare no expense. I found it difficult to get the socket on some of the bolts and a good one would have been very helpful.
To make a long story short, you need to pull the dash pad, some guys pulled the passenger seat, I left mine in and it was a contortion job, but OK to deal with. Pull off the two kick panels on the passenger side. The black one is simple, pull the ECM out. Removing the carpeted one is painful and requires mucho patience. The bolts for the carpeted panel face toward the front of the car. It was difficult getting the socket on them square enough to bite and get them to turn. Then you have to pull the bread box, again those bolts face toward the front, but some are easy because the dash pad is off. Then you have about 6 bolts that hold the heater core cover on, and the top ones are a pain to locate. Once you know where they are, putting them back in is easy.
Make 100% sure the replacement heater core is an EXACT match. There is a notch in the core that mates to the mount on the frame. If it is not right you will not get it back in. Took me 2 cores from different mfrs. to get the right one.
I spent a fair amount of time on my back in the passenger well, with my feet between the seats up into the hatcha rea, and an equal amount of time on my knees, bent over the sill. My chiropractor had a field day:)
Only burnt myself once with the trouble light:cool:
When I did my search in the Archives I found a website that described taking the carpeted panel off. It was very useful.
It took me about 3 hours to get the core out. But I have to spend more time on my dash pad than most due to depth of the speakers I have in there. It took me about 6 hours of evening work to get it back together.
Do not use thsi to actually dop the work, I am just trying to give you an idea of what is involved.
Hope it helps

Barrier

Thanks for the info, I will do that, but my first problem is now getting out the rear bolt on the Thermostat housing. 1 turn so far 2-3 hours I'm running out of patience. I'm gonna soak for a day or two, and then try again-- anybody have advice???
Trey thanks for offer but I'm going to buy a new one, I don't want to do it twice. 35 years ago on a 62 Bonneville I replaced a heater core, had it repaired, put it back, leaked pulled it out,they repaired and apologized. What a Bi--h. I do learn from mistakes--sometimes.
Barrier :) :)

payback1

Same thing has been happening for a while on my 1990. Now it happens at any and all speeds, even with the A/C completely off. The colder it gets outside the worse it is. Scared me the first time it happened, was cruising at about 65mph and all of a sudden thick fog fills the cabin. BTW, there is a greenish tint to it on the window

I checked the passenger side and there is no wetness anywhere. Could it be a plugged hose? Anything else a newbie like myself could check before unloading my wallet on this one? :p:

Thanks



[Modified by payback1, 9:19 PM 2/5/2002]

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BTT

Grzldvt

payback1,
How is your coolant level? Your leak may be small enough that it has not shown in the carpet yet. But if you are blowing green air onto the windshield, chances are very high you have a core leak. You can keep going until it gets worse, just carry some water with you to get you back.

cohocarl

I snapped the rear bolt right off flush with the base when I removed mine. :cry I tried using a stud extractor and it also snapped off flush. :cry :cry :mad After I had the base off of the motor, I could work on it easier, but I wound up messing up the threads so bad that I wound up drilling a hole all the way through the base, (doesn't hit any water passages) and putting a long S.S. bolt up through the bottom with some JB weld on the threads to keep it in there. I now have a "stud" on the rear thermo housing, but no big deal. The head of the bolt I stuck up in there had just enough clearance so it wouldn't hit the head when I re-installed the base. I have some pics of it if it comes to that (hopefully not). The coolant had corroded the threads of the original bolt so bad that it was NOT coming out. Luckily I didn't mess up the sealing area of the base where the thermostat outlet seats.

I don't know if you could take a torch to the bolt w/o melting anything around it, but if you heat it up, then squirt some WD40 on it, that may help.

Good luck.

Carl

payback1

Coolant level seems fine. It just recently started, im just wondering if it could be anything else besides the core. Im pretty much a novice when it comes to working on cars, so I dont know if I want to attempt this one on my own. From the posts here, it seems like a hell of a job :)