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Tue May 05, 2009 7:43 am

OK, 62 f outside temp (new york)
I started van up and set to about 2000rpms
It took 10 min to get to red light
13 min when fan came on, just over red light
Temp on hoses
Left of t-stat 82c right of t-stat 85c center going to rad. 78c
front of van driver side hose 71c other side 82c
water does boil on heads!!! 116c

Tue May 05, 2009 7:54 am

It sounds to me like Tencents is right on this one. Pull your thermostat and check it against measurements he gives.

Tue May 05, 2009 9:11 am

supdave66 wrote: OK, 62 f outside temp (new york)
I started van up and set to about 2000rpms
It took 10 min to get to red light
13 min when fan came on, just over red light
Temp on hoses
Left of t-stat 82c right of t-stat 85c center going to rad. 78c
front of van driver side hose 71c other side 82c
water does boil on heads!!! 116c

Yea, i agree with Tenc and WT, rule out the T-stat. Me, when T-stat out i would start the thing and look at flow. But that me. How is the water pump condition on that van?

13min to get the fan started, mmmm.... That's fast a 60 outside.
Was the head boiling only after 13min or so, if yes, that's not normal.
116C is way to hot.

Ben

Tue May 05, 2009 9:35 am

Mine ran fine without overheating when the wrong tstat was in there, but it read a little higher than normal. When I switched to the right tstat, same 87C rated temp but the right-sized disc, the gauge went down more than a full needle-width.

When you're shooting IR readings, you can't compare temps from the surface of a rubber hose to temps at the surface of a metal pipe; the rubber will be substantially lower. And a hotter component like an exhaust pipe within the field of view of the gun will raise the reading a lot. Just make sure you're comparing apples to apples.

Tue May 05, 2009 9:44 am

You may have more than one problem. The rad fan should not be running with the hose temps and rad temps you have posted. You must have the wrong temp switch installed in the rad, the one from some turbo Audis. It runs too soon and also makes you think you have a better flow to the rad than you do.

The hose from the thermostat cover is the cooled hose FROM the radiator so it should be lowest as it is.

The simplest answer is you have the wrong type thermostat in there. The right one closes one flow path as it heats and opens the main flow path. Where did you buy it? Did you put a brand new rad in or something used?

Mark

supdave66 wrote: OK, 62 f outside temp (new york)
I started van up and set to about 2000rpms
It took 10 min to get to red light
13 min when fan came on, just over red light
Temp on hoses
Left of t-stat 82c right of t-stat 85c center going to rad. 78c
front of van driver side hose 71c other side 82c
water does boil on heads!!! 116c

Tue May 05, 2009 10:12 am

I haven't measured head surface temp with IR, but I think it could commonly be over the boil point (coolant temp and head temp have to differ widely; remember, there has to be a temp slope for any heat to flow). I install temp registering strips on the cylinder bank, though, right below the water jacket gasket, and they typically show 220-230F.

I have been taking both IR and surface temps of those hoses in question, and those temps are not at all out of line. It is also very easy to get inaccurate readings with an IR gun; use a surface probe if you want isolated temp, or hold your IR gun as close to the surface as you can.

This may be just one of so many cases where someone thinks it's running hot, when it's not. I sure wish people wouldn't base that judgement on where their temp needle rides; it is completely arbitrary.

I have a customer, just installed a new engine from me, and changed his gauge temp sender at the same time. Said it was running a lot hotter than his old engine, well above the LED. Switched back to his old sensor and the gauge read low over the LED. There is not even the pretense of accurate calibration on these things, people! Do you see any numbers on the scale?

Have you verified the voltage coming off the chip that feeds the gauges? Verified that the gauge sender connection is clean and firmly attached? Did you do a basic gauge check: ground the sender wire and the needle should top right out, unground and it zeroes?

Because frankly I don't see anything really wrong here.

Tue May 05, 2009 2:05 pm

I just tried this with my 87. Started engine, put stick between seat and gas pedal to hold 1900 rpm, steady, waited a few minutes.

Read temp on top of left head, near end where thermostat housing attaches, right head in middle where I had a space to reach in. Temps gained at a steady rate for a few minutes. I went to the front and removed upper grill to check rad temps. The tanks gave low readings. After a couple more minutes I figured out that the metal edge that wraps over the tank edge gave the highest readings. When the driver side hit 92C the rad fan kicked on. I ran back and checked both heads. 98-99C, dropping to 95-97C while fan ran a minute. Both heads held steady until fan shut off then crept back to 98-100C. Fan kicked on again and temp slowly went back to 95-97C.

Heads 95-100C, fan cycling

Radiator metal edge high on tanks, peaked at 92-93C, then plunged when fan kicked on, crept back to 93C after fan off a bit, then fan ran again

Temp gauge at top edge of led, lowered slightly after fan ran, then back up while fan off

Shutoff engine and head temps went up, reaching 105C.

1987 pass, w/AC, 25C ambient, slight breeze from back of van

Mark

supdave66 wrote: OK, 62 f outside temp (new york)
I started van up and set to about 2000rpms
It took 10 min to get to red light
13 min when fan came on, just over red light
Temp on hoses
Left of t-stat 82c right of t-stat 85c center going to rad. 78c
front of van driver side hose 71c other side 82c
water does boil on heads!!! 116c

Tue May 05, 2009 2:47 pm

crazyvwvanman wrote: I just tried this with my 87. Started engine, put stick between seat and gas pedal to hold 1900 rpm, steady, waited a few minutes.

Read temp on top of left head, near end where thermostat housing attaches, right head in middle where I had a space to reach in. Temps gained at a steady rate for a few minutes. I went to the front and removed upper grill to check rad temps. The tanks gave low readings. After a couple more minutes I figured out that the metal edge that wraps over the tank edge gave the highest readings. When the driver side hit 92C the rad fan kicked on. I ran back and checked both heads. 98-99C, dropping to 95-97C while fan ran a minute. Both heads held steady until fan shut off then crept back to 98-100C. Fan kicked on again and temp slowly went back to 95-97C.

Heads 95-100C, fan cycling

Radiator metal edge high on tanks, peaked at 92-93C, then plunged when fan kicked on, crept back to 93C after fan off a bit, then fan ran again

Temp gauge at top edge of led, lowered slightly after fan ran, then back up while fan off

Shutoff engine and head temps went up, reaching 105C.

1987 pass, w/AC, 25C ambient, slight breeze from back of van

Mark

This is about what I would expect to see. An engine temperature just above the thermostat temperature and not a lot of temperature drop on the way forward to the radiator. I would guess that you are running a stock fan switch. With the replacement -75 fan switch I would guess that the engine temperatures would stay almost constant as the fan cycles.

I don't know if supdave66 ever mentions what year his rig is. There might be difference between years that would affect his readings.

Tue May 05, 2009 3:45 pm

My heads were at 116c. I Just ordered a new t-stat from bus depot. I will take some measurements when I get it. 33mm across right? They are in PA I should get it tomorrow.

Tue May 05, 2009 5:11 pm

I have a Suby 2.2 that is OBD2. The head temps and the reading on on the OBD2 scan gauge is always with in a degree.

If it isn't the T stat, it might be a bad water pump or head gasket.

Tue May 05, 2009 5:37 pm

Wow, are you married to his sister? I would have guessed Fri.

Mark

supdave66 wrote: My heads were at 116c. I Just ordered a new t-stat from bus depot. I will take some measurements when I get it. 33mm across right? They are in PA I should get it tomorrow.

Tue May 05, 2009 5:49 pm

I had the same overheating symptoms when the cap on my pressurized coolant tank went bad. If the cap doesn't hold pressure in the system then the coolant boils at a lower temperature. When my cap went bad the engine was only a little hot while running because the water pump kept the coolant flowing through the radiator, with rad fan running a lot. But as soon as I shut the engine down the needle would rise and I could hear the "stagnant" coolant boiling in the heads. Try a new seven-dollar coolant pressure cap and see what happens.

Tue May 05, 2009 6:01 pm

I have dealt with Matt at the bus depot before. If I tell him that I need it, he can get it to me in one day two at most.
I put a new water pump in last year. So I hope it is not the head.
Is it possible that I have a blockage somwhere?
I might try to run with no t-stat to see if that does anything.
Should I try to flush the system?

Tue May 05, 2009 8:27 pm

It's a bypass system, like a lot of cars. Running with no tstat will make it overheat badly, as there will be little to no flow from the radiator. Don't even try it.

Tue May 05, 2009 9:08 pm

Hey Dave,
Let's take a look see in the next couple of days. No offense to the the Bus Depot, but Van Cafe has a thermostat that opens at a lesser temp. I'm more familiar with the 1.9L, but to throw coin at something...

There also could be a cracked wire from the sender that could also be mucking things up.

Don't sweat it. I'm going to rebuild the rear cooling system ( pump and all) in my 1.9L this weekend. I'm game to come on over on Thurs. and go wrenching with you on your rig to get you to Granny G's.

Let me know.

Wed May 06, 2009 5:12 am

Back to bleeding!!!! In my bentley book is says (close bleeder valve in engine compartment after coolant flows out) That is a closed system, when I open that valve it just moves coolant up that small hose, but you can not see it.

Wed May 06, 2009 5:53 am

87c is what the van should have, putting a 80c is a band-aid on a more serious problem. Engine are design to work at a certain temperature.
If you consider the quantity of coolant a vanagon as and the fact that the engine is in the rear, the cooling system was well built.

When replacing rad a more serious bleeding is needed. But when i don't replace rad i basically don't even bleed the van.

So when engine/coolant work is needed in the back (around engine) always raise the rear first and leave it raise until your done. NEVER open the rad bleed screw and you won't need bleeding. By raising the van you help the front part of the cooling system staying tight.

When rad bleeding is needed, first fill (cold, engine not running) the system slowly until you see coolant coming out of front rad(rear wheel on ramp front bleed screw removed), when you have a nice flow put bleed screw on and close it, lower the van on 4 wheel, start engine a few time and fill EX tank if needed, close EX tank, now raise rpm to 2000 until T-stat open, open the rad bleeder for a few second at a time, if you leave it open pressure won't built up. After a few time you will start seeing a lot of air coming out, close it again a few time until flow is perfect.

in 6 years in the shop i have seen 2 T-Stat related problem, only 2, one defective new one and one old one.

I test ALL new T-stat just to see if they will open, the defective one was stuck close.

Ben

Wed May 06, 2009 7:13 pm

What if I have a blockage. I was thinking of flushing the system. Do you think that will help?

Wed May 06, 2009 7:33 pm

Are you saying that new thermostat that arrived today did not help?

Mark

supdave66 wrote: What if I have a blockage. I was thinking of flushing the system. Do you think that will help?

Wed May 06, 2009 8:21 pm

supdave66 wrote: What if I have a blockage. I was thinking of flushing the system. Do you think that will help?

Listen men (i call you men because.. well, it seem that everyone here is afraid to use their real name and location, this i so funny???? We share stuff, get personal is some ways but we use stupid online name... end of rant)

So Men! i feel you pain and i fully understand the stress you are having right now, welcome to Westy land, or should i say VW land. The love and hate relationship land. The rust, dirt and dust land.

What you live right now i deal with that everyday. Strange and bizarre problem. There is always a solution but sometime, time is what you need! No way out.

So now, wait for that thermostat and rule that one out. And i could bet it's not you problem but i will shut the hell up because sometime, it look like i know to much and i don't want to act like the guy who know everything. And i could be wrong. And sometime i am... wrong.

You said that it's after you change the thermostat and the sender that everything went wrong! So we would assume that you created a problem so everyone is assuming that the problem should be associated with something around the thermostat... but for some strange reason, maybe something else failed. Not because you played around the T-stat but because it's a frigging fact that stuff happen for no reason.

So NO, you don't have a blockage, i don't believe so. So rule the T-stat out and we will see after. You change the rad so that is one less big problem that we can rule out. The only next step is flow.

I do think the engine is to hot. That frigging needle should be called the stress needle :-)

Ben