OT Car Problems OT

I don't know. Could it be trapped air?

.......... and yeah, its better than politics!

Does the radiator hose on the pump's suction side collapse at higher engine speed?

-jsw

First off, make sure you have a tstat in there. The engine's thermostat is necessary to allow the radiator water to warm up to proper temp for delivering how air through the core. In addition to that, the water pump is responsible for flow. I've seen water pump impellers eaten down to nothing via electrolysis and rust, so don't rule that out.

You said you checked the water control valve, and it's OK, as is the heater core? Restrictions there are usually the culprits if the water pump and thermostat are operative. Make sure that the water control valve for the heater is properly adjusted. Some are extremely picky, especially if the water pump impeller is diminished. Also, try to see if the water control valve gate is loose from the arm. I've seen the shafts break but the arm not fall off.

As to heater core flow, can you blow a full lungful of air through it without any back pressure whatsoever? Maybe boil it out, just to be on the safe side? (Egad, it has been so long, I don't remember what that entails any more!) If in doubt, go to a Toyota dealership and blow through a replacement core to note the difference.

Let us know what you find. Curious minds, etc.

That poor guy needs a better _sound_system_.

Yeah, I guess if the rad was that badly blocked, it would impede the flow through the core, too, wouldn't it?

Nope , all hoses are in like new condition - the guy I bought it from had a lot of work done to it . My neighbor worked at the shop that did the work , and IIRC all hoses were replaced along with fan and cam drive chains/belts .

There is a t-stat , motor comes up to op temp in a reasonable time . I hadn't considered a prob with the impeller , but doubt it's the problem - I think there's an intermittent blockage but I can't find it .

Valve operates correctly and is not broken .

Core shows no sign of restriction when I run water thru it . I'm not inclined to completely disassemble the dash to pull the core . I was sure I'd find a hose with a degraded inner layer that was blocking the flow , but the hoses are all in like-new shape , and I'm stumped . My next step is to drain the whole system again and run some kind of chemical flush thru it , it's possible there's a flake of something floating around the intake man passages , but I don't understand why it doesn't flow out to thru the t-stat into the rad if that the case . I'd much prefer the wife to be warm rather than hot , if you know what I mean .

Still check your engine thermostat. The thermostat's purpose is to keep the coolant flow out of the radiator until the engine comes up to operating temp. The engine warms up on its own, then the thermostat admits the hot water to the radiator/ heater core. If it isn't opening, the engine will still warm up, but nothing else will.

Paul K. Dickman

I am stumped too. When you flush the system , do you get anything out or d o you just get clean coolant?

I suspect it is just clean coolant. It sounds as if you have something in the line that moves to a place where in blocks the coolant flow. If it wer e in the engine coolant hoses or radiator , your engine would be overheatin g.

I would try back flushing the heater and heater hoses. That is have the fl ushing water going in the opposite direction from the normal flow. If that does not have anything come out of the system , then try flushing the othe r way and see if there is a good flow rate. If the flow is restricted , th en you just need to figure out where. So check the hoses and then the heat er core.

I think the most likely place for a clog is the temperature control valve. Probably the hardest place to check.

Dan

You are 100% sure? Did you take the hoses off both ends and look to be sure when the shaft moves the plunger or "spool "moves too? VERY common problem on earlier Toyotas - not sure if 99 had the problem or not. As Toyota service manager I had a LOT of them replaced.

If the engine comes up to operating temperature in a reasonable amount of time on a cool day, the 'stat is not causing the problem. I'm still betting on a bad heater water control valve.

It's a ball type valve , and it is functioning correctly , the ball cannot be moved on the shaft . First thing I checked .

I've flushed both directions , no impeded flow . The valve is mounted on the firewall inside the engine compartment and is very easy to check .

So call and ask the mechanic/musician what color guitar pick to look for.

You didn't answer my "lungful" question.

The potential for a collapsed inner wall was a good one. Pull the heater core hoses and put a funnel to one side. Now dump a gallon of very hot water through it and see if the heater blows hot air. Also note how fast it passes through there. It should speed right through.

Ayup.

If it is a ball valve they HAVE addressed the problem.

Is the hole in that valve as big as the heater hose ID ? Try pulling the hose and starting it to check for flow. Might try bypassing the valve any way - winter is almost here. Hope your tests don't point to the pump. ww

I hope not too , but if that's the problem I'll fix it . I have my doubts , all indications are that there is some foreign matter blocking a passage or fitting . The wife's assessment for today is "Better than it was but not as hot as it should be." .

As stated before, bypass the valve and see what happens. A bad pump would almost certainly result in a very quick overheat incident. It has every time it has happened to me. (twice on my own and 2 or 3 customer vehicles)

I would say it is the thermostat. Block off flow to the radiator and there will be more heat from the heater than you know what to do with.