Cooling problem

[Luckypabst]

I'm pretty sure it's the water pump - what do you guys think?

Driving home last night in the Van, I noticed the heater rapidly loosing heat, then looked down and saw the gauge cruising to the top end, red light flashing.

Radiator was cold, coolant was boiling in the head, no blown hoses or other soaked undercarriage to indicate coolant loss. I let it cool down, turned the engine by hand to verify that it wasn't hydrolocked and continued down the road with the heater 'coming and going' and the gauge needle climbing and dipping somewhat.

I think the impeller spun on the shaft and can't think of any other reason that the heater would quit heating in conjunction with the cold radiator and overheating engine.

Also my shifter gave up the ghost in the process.

Chris

[53 willys]

kinda sounds like the t-stat to me.......you'd think you would hear the impeller bouncing around if the pump was gone??

[Luckypabst]

The heater would still work with a stuck thermostat but that was my second guess (after assuming I'd dumped my coolant).

[Luckypabst]

Here's what I've found:
-Thermostat opens as expected, maybe a bit high, closer to 212 degrees but I may be bringing the temp up quicker than reasonable and the thermostat can't keep up. I'll probably replace it since it's out.
-Water pump impeller is nice and tight with the "jam a screwdriver in there and turn the pulley" test.
-Just before the incident I kept hearing a strange bubbling noise from the heater vicinity. This was the first long, high speed run since having drained most of the cooling system (and the heater circuit). I wonder if there was an air pocket in the heater that finally blew out into the main cooling circuit, cavitating the pump and rendering the pump useless. On the trip out it was warm with the heater off. Coming back just after midnight we had the heat on. Otherwise it did fine on the 7% grind out of Panamint Valley before opening the heater valve...

Any thoughts on my theory?

The shifter pivot ball blew apart. It had been giving me trouble, intermittently and it decided last night to completely disintegrate. VanCafe to the rescue again...

Chris

[molgrips]

I've found that it can take bloomin ages to get all the air out of the coolant system after a drain...

HTH  :lol:

[jtanguay]

I've found that it can take bloomin ages to get all the air out of the coolant system after a drain...

HTH  :lol:

amen to that.  almost a good idea to put vacuum in the system to suck the air out  :lol:

[Luckypabst]

Got it worked out - I drained the coolant to check the thermostat and water pump. With the heater valve opened it took an additional 1.25 gallons more liquid that what came out.

Chris

[Luckypabst]

It happened again yesterday. Running hard for about 20 minutes and it pegged the gauge with the little light flashing - turns out it's a bad head gasket, caught early on.

The "quick pressurization" test doesn't really work on a vanagon, at least not with a small leak like I have. I suppose the 898989 feet of hose take a while to show any pressure increase.
Keeping the coolant reservoir topped off with coolant and the revs up to about 2k revealed a steady flow of tiny, foamy bubbles and occasionally larger bubbles.

I guess the fiber gasket isn't 100% reliable at 18 psi. ARP studs are on their way and I'll be ordering an AAZ gasket shortly (I'd really like to gamble on a fiber gasket and studs but I'm not much for gambling).

Chris

[captainpartytime]

I had a very similar situation in my westy with the original n/a motor. Gurgling sounds in the head followed by fluctuating temps. Same result --- head gasket failure followed closely by a hydrolock. My rebuilt TD motor got ARP studs and the metal head gasket. I think this will be a relatively bomb proof solution. Now I just have to get the motor in the van!

[allsierra123]

well atleast you caught before it was too late.

[Luckypabst]

I got the head off today, somewhat nervous but bolstered by the AAZ gasket and ARP studs in hand.

I could only find one little spot that looked like the gasket lost its seal and seeped combustion pressure into the coolant passages - if that was it then this was a very minor leak caught extremely early on. I'll pressure test tomorrow and know the full story but I think I'm good to go. The surface looks to be well within spec for flatness which is what I was most worried about.

The regular cracks between valves and in the precups are there but nothing terrible. I was pleased to see zero valve prints in the pistons - this engine only has about 45k on it and 25k is mine but I was skeptical after seeing soooo many pictures of slapped pistons - I began to think the swirly round prints were machining marks.

Chris

[Smokey Eddy]

I was pleased to see zero valve prints in the pistons - this engine only has about 45k on it and 25k is mine but I was skeptical after seeing soooo many pictures of slapped pistons - I began to think the swirly round prints were machining marks.

ME TOO. My pistons have 1 print on each. Pretty deep ones too . not just a print but an indentation. Phew, glad I got a new head on it's way.

[ragulka]

Hey, didn't want to start a whole new thread since I also seem to have problems/questions with the cooling system.
I just got my vanagon back from the mechanic, who installed in a 1.6TD engine from Golf Mk2. Everything was great for about 2 days, then I noticed, that the temp gauge was going almost 3/4. It stayed there so I didn't do anything at first. On the 4th day the gauge went up very very fast and started blinking red. I discovered that the hose to front heater was broken and there was a little bit of steam coming out from it, it was also leaking.
So i replaced that and I also thaught that the thermostat might be broken, so I took the old thermostat from my old engine and put it in. There was a difference between thr two: the on I had in was very very hard to open with hands, the one I took from the old engine was pretty easily opened by hand, and it had small, about 1/2 mm holes drilled thru - it seemed that it is how it was built.
Anyway, I drained and refilled the system (I did that on a slope, so that the expansion tank would be higher than the radiator bleeder valve). Woohoo - overheating was gone! BUT - now it didn't get warm - the temp gauge read about 1/3 which I know is too little, it should be right in the middle... And the heater didn't get warm at all. So, I bought a brad new thermostat (just like the on I had in first - without the tiny holes), drained, refilled again, on a very steep slope to ensure the expansion tank was way over the bleeder at the radiator. And voila! The engine started to warm up quickly and stayed in the middle, also the heater started to get warm when the temp gauge read about 1/6.

My question is - what are those little holes for in the thermostat - is it to allow some coolant to flow back from the radiator? Could it be a necessity in hot summer days?

[clbanman]

I'm pretty sure it's the water pump - what do you guys think?

Driving home last night in the Van, I noticed the heater rapidly loosing heat, then looked down and saw the gauge cruising to the top end, red light flashing.

Radiator was cold, coolant was boiling in the head, no blown hoses or other soaked undercarriage to indicate coolant loss. I let it cool down, turned the engine by hand to verify that it wasn't hydrolocked and continued down the road with the heater 'coming and going' and the gauge needle climbing and dipping somewhat.

I think the impeller spun on the shaft and can't think of any other reason that the heater would quit heating in conjunction with the cold radiator and overheating engine.


Chris

I had a situation with identical symptoms on my Golf.  Turns out it was caused by a loose belt in combination with a heavy rainfall that created a situation where the belt was slipping enough to keep the coolant from circulating but the belt wasn't squealing due to the water.

[passatdiesel]

something not to rule out is your lower rad hose, due to the age of our vehicles. One simple check is once the engine is at operating temps, feel the lower rad hose for heat and unusual soft spots, this will help indicate weather your hose is seperating inside and restricting flow. What I've found from personal experience is that the more of a load you put on the engine, ie hard prolonged accelerations, or highway speeds will cause the engine to overheat, since the flow is restricted, your boiling the trapped water, causing your coolant system to overpressured and possibly simulates an airlock.
That is how I interpreted the bentley manual, I'm sure someone will have something to add or correct if I'm wrong.