V70 1997 Heater problem

Post by **pfeener** » 06 Mar 2006, 15:01

Sounds like you're making some progress. I wouldn't replace anything just yet. If we sit back and analyze the problem; after you flushed the system, the problem got somewhat better; which says to me you have a clog somewhere because if the system had been free and clear to start with, flushing it wouldn't have done anything at all. Also the fact that one of the heater hoses is hotter than the other says to me that you're not getting the volume of flow through the heater core that's necessary. There's not any mystery in the system itself; the antifreeze flows out of the hose which is plugged into the cylinder block and flows into the top heater hose connection, flows through the heater core unobstructed (no valves to shut off the flow) back out the bottom hose and into the return flow from the bottom of the radiator and back to the pump. Having said that, here's what I would suggest; 1. flush it again with a flush agent that you can leave in longer. Some flush agents are made to stay in for a few hundred miles. 2. If that doesn't do it, I would consider changing out the heater core. It's a good sign that you can flush a hose through the heater core, but it doesn't necessarily mean it's OK. The heater core is built like a mini radiator in that the water flows into a tank on one side of the core and then through a couple dozen small tubes to get to a collecting tank on the other side of the core. If half of the tubes are clogged you'll still get flow through the core, but only half the core will heat up and you won't get much heat.

If you flush it again you might also try back flushing the hoses that feed the heater core just to be sure they are free and clear.

The root cause of the problem could be that the previous owner had a leak in the heater core and dumped in a can of "stop leak" which stopped the leak but clogged the small tubes of the heater core; so even if you get it running free, you may get a leak back in the core anyway.

Just curious; how did the antifreeze look when you flusshed it. Was it relatively clear of did it have a lot of junk in it?

Post by **pfeener** » 06 Mar 2006, 15:10

Missed one of your questions again: The water pump is probably the last thing I would suspect. It's just a bunch of vanes spinning around. If the vanes were eaten away (never ever seen it happen) the flow would be affected, but you'd have far bigger problems such as the engine overheating. I still think it's in the heater core and another more through flush may take care of it.

If you order a heater core, the aftermarket cores are a lot cheaper. FCPgroton.com, has a heater core for around $128.

rohosub · Post by **rohosub** » 06 Mar 2006, 16:21

Thx again, Pfeener.
When I emptied the system and flushed it, the antifreeze was greyish and smelly. It didn't look good at all. Even during my second flush grey stuff came out.

I think I'll follow your tip and go for yet another clean/flush routine.
Does anyone know if it is possible to use more potent cleaning agents than radiator clean without damaging hoses, inflicting corrosion etc?
Any chance I could inject stuff like an ordinary "drain opener" into the core itself as long as I don't run the engine? (Just a thought). A typical drain opener would consist of pretty potent NaOH which would eat away at almost evrything (Maybe also the aluminium in the core...?)

If a second drain/flush doesn't work I'll order a new heater core and try the replace myself using the guide posted here.

I'll keep you posed. I might take some pictures as well...

Thx again for your help here. It has been really helpful.

roho

Post by **pfeener** » 06 Mar 2006, 17:43

Some people use white vinegar when doing a flush. Here's a link with additional info. I wouldn't use anything like drain cleaner or such. I'd be too scared of dissolving things like head gaskets.

Personally I would look for a commercially available flush that states on the can how long to leave it in and as I said before, I would go for something I could leave in for a few hundred miles.

P.S. If your coolant was grey after the flush I would lean very heavily toward a clogged heater core. You may need to flush a few more times yet.

Here's the link:
http://volvospeed.com/vs_forum/index.ph ... hl=vinegar

Post by **kcodyjr** » 05 Jan 2014, 01:37

Drain cleaner? Sodium hydroxide? What are all yiz smoking and why haven't you offered to share??!!

+1 heater core. If it's so plugged the first flush didn't get it, just replace it. They're not terribly hard to get at. Don't screw around with aftermarket; they're irritatingly variable in quality, some need to be washed in soap to remove a film that would otherwise stink up the car, and they never last like the OEM Behr units. Get the real McCoy.

I don't even know how this ancient thread got opened in my browser, but REALLY?? Lye??!!

Matt, I'm asking if you might open a poll. I'd like to know what's the most f**cked up chemical people have actually known for sure some idiot dumped into an engine. Just for kicks. Please??

c70_lindsay · Post by **c70_lindsay** » 06 Jan 2014, 14:27

I know it's an old post, But I had a simililar problem with my C70. I blew out my cabin air filter with a compressor and it worked fixed the problem.