Another no-heat report

[skibo]

Last winter my wife reported the heat was weak in the Volvo, but I wasn't convinced. Now that the cold weather has returned, I'm convinced. I read all the posts on this topic here and at Howard's site, and started with the replacing the 5 year old cabin air filter - no help. Then yesterday I pulled the ECC, removed the little fan and cleaned the fan and sensor - both had some dust on them, but nothing major, and the problem persists.

When I face the car and touch the heater hoses, the one on the right is hot, and the other is just luke warm, so I have to think that I'm not getting flow through the core. Does this mean the core is plugged, or is there a valve in there that might be stuck closed?

Any thoughts are appreciated.

[skibo]

Hmmmmm.....nobody has any opinion on that.

From the instructions posted in the resource section, there does not seem to be a valve, so I'm leaning towards a plugged core ( although I'm not sure why that would have happened - I don't see any other reports of that on here ). But rather than replace it right off the bat, I'm going to try a back-flush. It looks like the heater hoses just pull off of 2 barbed pipes at the firewall. Can it really be that easy? That doesn't seem very secure - I'm surprised there isn't some fancy clamp or something on there.

[Aviator]

I'm surprised there isn't some fancy clamp or something on there.

There is, and there is a special tool for getting those hoses off. By the way, where is your temperature gauge reading when the engine is warmed up? One heater hose will always be hotter than the other, but not by much. I doubt if it's a plugged heater core.

Dave.

[skibo]

The gauge is vertical, like it has always been. The one hose is very hot and the other is only warm - significantly different temperature. I was also surprised to find this, as I've never used any sort of 'Bars-leaks' or anything similar. I'm still not 100% convinced, but everything else seems to be checking out - last night I confirmed that the little levers near the core move when I change the temperature setting. That's why I wonder if there is a water flow valve somewhere that is stuck closed.

The instruction posted in the resource section makes the special pliers look like long vise-grips, and seem to be used only to seal off the hoses. Although I'm not sure why that is nessesary since the hoses seem to be the highest point in the system.

[Aviator]

The gauge is vertical, like it has always been. The one hose is very hot and the other is only warm - significantly different temperature. I was also surprised to find this, as I've never used any sort of 'Bars-leaks' or anything similar. I'm still not 100% convinced, but everything else seems to be checking out - last night I confirmed that the little levers near the core move when I change the temperature setting. That's why I wonder if there is a water flow valve somewhere that is stuck closed.


Okay, so temp gauge is reading okay. Any coolant leaks? Reservoir cap sealing properly?Is your top rad hose nice and hot? If you pull down the plastic sound panel, right where your knees would be, you can get your hands on both tubes connected to the core itself. Try that and see how hot they are. Normally, with a plugged core or partially plugged core, it sounds like water running through the dash, almost like water flowing through a drain pipe from a toilet, and it changes when cornering the car. There is no water valve, by the way.....those disappeared years ago.

Dave.

[skibo]

I finally got back to this today. Once I looked at the connections in the daylight, the diagram in the Volvo instructions makes complete sense. There is a spring loaded ring at the firewall that rotates 90 degrees to the left by hand - then the elbow pulls right off of the barbed nipple. It pushes back onto the nipple with a slight click. Very nice design - extremely easy to take the hoses off once you know how.

Once the hoses were off, I flushed the core from left to right - I had a 5/8" ID garden hose with a valve on the inlet and 5/8" ID clear hose on the outlet going to a bucket. There was no obvious 'bang' or 'pop' when I put some pressure to it, but i could see stuff in the outflow through the clear hose - it looked like the scum that builds up in my kids' aquarium filter. Not the hard chunks i was expecting, but more like off-white chunks of slime.

I put 5 gallons of clear water through it, put everything back together, and the heat is back! I'm not sure it's running at 100% but it's vastly better than it was before - I wonder if there is something I can put in there or through there to really clean it out well. I saw someone suggest vinegar, but I'm not sure what that would do.


<< search terms: heater hose removal , heater core flush >>

[06ORXC]

If U are in a need of a coolant flush anytime soon I would recommend to drain the whole system including overflow tank now.
Running distilled water only thru couple of full heat cycle to break up any garbage in a cooling system with a drain in between.
Refill with fresh volvo coolant and enjoy.

[skibo]

Hmmmmm......won't running with just water hurt the water pump seal? I thought the 'slipperiness' of the antifreeze was at least in part to lubricate the water pump seal.

At 146,000 miles on the original seal, I'm leery. (knocking wooden window casing)

[06ORXC]

I'm not talking about driving anywhere, few minutes won't hurt anything.
Plus,U can never get 100% of antifreeze out so some will be there.
Drain it from the inlet of oil cooler by the steering rack.
Drain old coolant, fill with distilled water, run up to operating temp., drain same way, fill and run, drain it all and fill with fresh volvo coolant.

[skibo]

Ok - another winter is approaching and the heater core is plugged again. I blame myself since I've put 8.5 years and 160,000 miles on the factory coolant, which is now a sickly flesh color. So today I got a gallon of the OEM coolant at the dealer ( only $20 out the door ). Planning to back flush the heater again and the run the Prestone flush stuff through the engine before a final drain and fill with plain water and then a final refill with the 50-50. I understand there are 2 peacocks on the system

My two questions are
1). With no radiator cap I think the only means of filling is through the overflow tank - how do I vent the engine to avoid a bubble ?
2). Although I haven't had any overheating issues I'm thinking of back flushing the radiator, but I'm not sure if the normal flow through the radiator is top to bottom or bottom to top.?

Any help appreciated.

[skibo]

I backflushed the heater core again today, and as happened last December, I got out some junk and the heat instantly returned. Attached find a shot of my set-up. The green garden hose is the inlet, and I have a ball valve on it for local control, and the clear tube on the right is the oulet to a bucket. This time I had my 9 year old run the outlet water through a fine sieve, and the 2nd shot is the total gunk I got out of the core. It's maybe a rounded teaspoon at best - i'm surprised this could stop up the heater core, unless the tubes are corroded nearly shut.

[06ORXC]

My suggestion from almost year ago are still valid and would help with this problem...

[skibo]

Ok - flushed with tap water - ran for 2 days with Prestone Super-flush - then did 4 cycles of drain/ fill-with-distilled / run-up-to-temp / repeat, and did a final fill with 1 gallon of OEM coolant and the rest distilled water. We'll see what happens.