Cooling woes

[RunninWild]

Long story short I removed my water pump and installed it onto the older style housing that uses 1 less bolt. I'm not getting any leaks but I don't think the coolant system is flowing (or there is a massive airlock stopping flow). After idling The engine for 10 or 15min The water outlets and the head are hot enough I cant hold my hand on them. The 2 hoses coming out of the top of the head are hot. The very top of the rad near the coolant inlet is hot. The rest of the rad is cold. Lower hose is cold. No heat in the vehicle my stock gauge reads about 3/4 towards hot after market gauge reads around 190f (not sure how accurate this is) but both gauges use their own sensors.

I originally thought it was an airlock but I'm starting to think the water pump isnt working. What could cause a new pump that's worked in the past to up and quit after re and re? I did try and get a smaller belt stuck on it. It was enough to bend my alternator shaft. Think it's possible the wp shaft snapped or something along those lines? Wouldn't the shaft just pull out of the pump if that was the case?

Is it worth draining The coolant for probably the 10th time and replacing the pump? Its cold, it's snowing and I'd prefer to avoid that is possible.

Anyone got any ideas?

[RunninWild]

Just replaced the water pump and thermostat. Rad and Lower hose are heating up now and temperature is stablr around 175f at idle. However I still have no heat inside the truck. I'm gonna try bypassing my heater control valve and hopefully that's the problem.

[RunninWild]

Just bypassed the heater control valve. No coolant came out of the lines when I disconnected them. Blowing into the heater core eventually got coolant to flow out of the back of the head. Thinking now it's just a huge air bubble. Gonna fill the lines by hand then connect them and see what happens. Will post back.

[RunninWild]

So I burped air out of the heater core manually, now I have some heat inside the truck. It gets warm At best with my gauges reading operating temp.
At operating temp the inlet to the heater core its quite hot to the touch. The outlet is lukewarm. After a quick 5min drive it started overheating. Upper rad hose was quite hot, rad fans were on (havnt dialed in the on off temps with my fan controller yet) and the rad was cold and the lower rad hose was cold.

What's everyone thinking? The new thermostat is faulty?

[ToddA1]

Sounds like you have some type of blockage in the heater core.

Thermostat shouldn't affect the heater core all. Not sure about the overheating part....

-Todd

[RunninWild]

I don't think it's blocked. Couldn't feel any restrictions in when I blew through it. The fact the out hose is colder then the in hose to me means it's acting as a little radiator exactly like it's supposed too. I can also feel coolant flow when I squeeze the outlet hose. I'm not sure what's up with the temperature it's putting out though.

I'm thinking the new thermostat isn't opening. Its the only thing that makes sense to me.I don't see how the lower rad hose can stay cold and have the engine overheat if it's opening and coolant is flowing? I'm gonna let it cool down over night so it can heat cycle. Maybe I'll get lucky and it's just a bit of air that needs to work loose. Tomorrow If the lower hose is cold and the 2 inlet hoses in the pump are hot it has to be the thermostat correct? I just texted the one I pulled out and it's working. Started opening around 80c and around 95c it was fully open. I'll throw it back in and see what happens...

[TylerDurden]

I'm thinking the new thermostat isn't opening.

Ja, or the WP impeller is spinning on the shaft. Coolant is def not flowing.

Long odds that the head gasket is leaking... if there is no rapid pressure buildup in the coolant tank, rule that out for now.

[RunninWild]

The impeller was tight with the shaft, I played with it a bit before I installed it. I don't see how it could have broke loose once installed. I can also feel coolant flowing when I squeeze the hose coming out of the heater core. I really think its just the thermostat. Im going to replace it today and I'll post back.

I did just change the head, and I did reuse the mls gasket (after cleaning and copper spraying each layer). That being said my oil and coolant are both clean and there are no bubbles coming up the reservoir and the coolant isn't building excessive pressure.

[RunninWild]

No luck with the thermostat. Still have the same problem. Thinking of bringing it to a shop an having it pressure tested and flushed. I don't see what it could be...

Does anyone think changing the head and reusing the gasket could be causing this problem? The exhaust isn't smoking and both the oil and coolant are clean. I think I have a clog somewhere but its not making sense to me.

Disconnecting the hoses at the heater control valve if I pour water into the hose going into the head it comes out the other hose coming from the heater core. To me this means it's free flowing and doesn't have an air lock, yet the the majority of the of the hose from the heater core To the oil cooler and wp isn't warming up.

If I turn the heater fan off for a few min then back on it's warm for a few seconds then cold. Its like the cooling system is bypassing the heater core section. At the same time the lower rad hose is cold and the engine is maintaining temp at 185f at idle.

[ToddA1]

The heater core is a heat exchanger, but both of my hoses get hot. I'm sure the outlet is cooler than the inlet, but it's not enough that I can feel the difference.

Was your blower on?

-Todd

[RunninWild]

Pretty sure I figured it out while I was sitting on the greyhound on my way to buy a car so I could have something to drive 


New style housing on the left old style on the right.
Look at the funnel part in the middle That feeds the pump. The older style is a smaller diameter and has steeper walls. Because I'm using a newer style pump I'm assuming the opening isn't large enough to supply the pump with coolant which would explain why I'm have no flow, or very little flow.

**Just so the information is out there the newer pumps are not compatible with the older housings**

[urmas]

I have a problem similar in a way that i dont get much heat in the cabin, though my cause is (i think) the measly amounts of heat produced by the TDi engine (AFN). In temps here at the moment (sub freezing) the car actually cools while idling with the heater fan on. Lower rad hose is always cold, and the MK2 temp gauge never climbs to the middle of the gauge where it used to be when the car had a gasoline powered engine.

Flap job in the heater box has been done, that helped a little.

[VW Smokr]

Once "boil-tested", for one of our commercial shop customers, a new thermostat (for a garden-variety sbc V8, of all things!) we'd sold him / his mechanics had installed for one of his repair shop customers. It was defective, wouldn't open... at all!

Then tested 10 other new, same model, right-out-of-the-box units from the same well-known manufacturer: 3 stats failed! Freakin' 30% failure rate! Later another shop owner mentioned that many thermostats today will only open if there's significant pressure behind them and in the presence of enough anti-freeze/coolant to raise the cooling solution's lubricity well above that of pure water. Ummm... sounds like crappy manufacturing & lack of quality control to me, but IMO that's unfortunately rampant in almost every field of repair parts today.

Fortunately the German thermostats are still available here in N.Amer. & do seem quite reliable, but I still "boil-test" any unit, new or used, that I install & also allow room for a bottle of Redline's "Water Wetter" in the cleaned & refilled coolant system as well.

YMMV

JR
SoCal

[RunninWild]

The first time I installed this engine with a new thermostat it was stuck closed. The 2nd one I installed worked fine before I overheated the head (cooling fan issue). The thermostat I'm using is the one that was working previously, and tested to be working in boiling water. Its only a few months old with maybe 100km on it and I doubt it's the problem. I'm really thinking this is related to the pump housing as I just don't see how it could be anything else. I bought a new car (2002 Acura 1.7 el) so I'm not in a rush to get my samurai back on the road. I'll try and update this thread when I change the pump to the older style and hopefully it's good to go!

[theman53]

Are you running only vw cooling hose routing and overflow bottle? Or are you using some of the sami stuff? If you blended the 2 you are in for a bad time. Search Jimfoo and his RR, he had to add a second T stat in line to take care of the issue