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I found a telling symptom of my cooling system woes
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vanagonforever
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PostPosted: Sat Dec 05, 2009 6:53 pm    Post subject: I found a telling symptom of my cooling system woes Reply with quote

I've been fighting with my cooling system for about a year now. It all started last winter when I decided that something was wrong since my Vanagon's heater didn't blow hot air. I pulled my thermostat and sure enough it was stuck open - I popped in a new one and figured that I'd be good to go. Sadly this was the beginning of my world of hurt.

With a working thermostat I get great heat but I am constantly overheating. I decided to throw a few cheap parts at the problem and went ahead and replaced my temp 2 sensor and temp relay on my thermostat housing along with coolant expansion tank level sensor with no change to my situation. My fan was never kicking in either so I went ahead and replaced the thermo switch on it just as a precaution but honestly I knew the radiator wasn't getting hot enough to trigger it. I did a lot more driving and I saw a problem where I would fill the coolant reservoir and then my expansion cap wouldn't allow my expansion tank to suck the excess coolant back in and this would trigger a dash warning light due to the low coolant level in the expansion tank. To deal with this I replaced my expansion tank cap, coolant hose from the expansion tank to the overflow tank, and put in a brand new expansion tank. All of that helped my situation but I was still running hot in traffic no matter how many times I tried to bleed my cooling system using the libby bong.

I was still running the original radiator so I decided to just replace it with a new one. With the new radiator in place I thought I was good to go and for a while everything seemed just fine. Driving down the highway I was sitting right in the middle of the gauge but as soon as I would pull off the highway and sit at a traffic light my gauge would crawl to the right and eventually overheat if I didn't get moving again.

After fighting this for a bit I decided that the thing to do was to install a manual override switch on my radiator fan that I could control from the dash. I wired a switch to kick the fan into high and while the switch works it doesn't seem to have much impact on the temperature in my thermostat housing.

Here is where the question comes in... Today, while it is cold outside, I let the van run at around 2-3k RPMs for a very long time and the gauge sat happily in the center just over the led. I thought that was interesting but I wondered what would happen if I let the van idle. When I let it idle for a few minutes the needle made a run for the right and the vanagon started to overheat. My LED started blinking but instead of turning on the fan manually (it didn't kick in on its own at either speed) I decided to rev the engine. After a few minutes at 2-3k rpms the gauge was right back in the center and all was well.

This tells me that my problem is flow. I swear I've followed every post on this board for bleeding my system, I've traced every hose looking for leaks, and I've tested my cooling system pressure and I have not found any other problems. While I haven't tried the flow test from the Bentley or replaced any hoses I also haven't touch my water pump. It seems as if my pump is working fine when the engine is under load but it just isn't pushing enough fluid at idle and the Vanagon overheats.

Now I've got a pretty rough idle right now. In fact it will even stall at times. Should I just go ahead and put in a new water pump or should I run additional tests. Can the water pump be impacted by a rough idle. Any other insights?

Thanks folks!
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tencentlife
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PostPosted: Sat Dec 05, 2009 7:19 pm    Post subject: Reply with quote

Sorry, didn't read every word, but have you tested your "good" t-stat in boiling water? Your general symptom set sounds like it's not opening.
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vanagonforever
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PostPosted: Sat Dec 05, 2009 7:21 pm    Post subject: Reply with quote

yes I did test the thermostat in boiling water and it behaved correctly
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imnotright
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PostPosted: Sat Dec 05, 2009 7:42 pm    Post subject: Reply with quote

Okay I had similar overheating problems in my 84, I replaced the water pump, thermostat, temp 2 , expansion tank cap etc... I knew my heads were done prior to my ownership so I ruled them out...

Question? Can you run with the expansion tank cap off when it overheats? Did you replace the cap?

So why did I ask this well... my light flashed and the needle told me I was overheating but I could run with my cap off touch the coolant but i did not feel it was overheating, so after calling a local tech he told me that Vanagons are plagued with electrical problems so I install an electric temp gauge from Auto Zone and have no problems since.

Hope this helps

Kyle
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funagon
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PostPosted: Sat Dec 05, 2009 8:02 pm    Post subject: Reply with quote

It sounds like your radiator fan doesn't come on when it's supposed to. That sounds like the problem to me!
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wcdennis
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PostPosted: Sat Dec 05, 2009 10:10 pm    Post subject: Reply with quote

I would say the slow idle could have a lot to do with your problem. The water pump spins with the engine, after all. It can't move much coolant if it is not turning very fast. I have also read discussions about some after market pumps having poorly designed impellers. It sounds like you have replaced everything else maybe a better pump should be on the list. I would see if you can get the idle sorted out first.
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Terry Kay
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PostPosted: Sat Dec 05, 2009 10:14 pm    Post subject: Reply with quote

If for some wild reason if at idle the expansion tanks fluid level drops--the temp gauge will rise & lights will go off--blinky blinky--

If the coolant level sensor is dirty the same thing will happen--big temps, and more blinking.

Yor Van may not be overheating at all.

Do you have a infared temp gauge??

I'd be verifying temps all over the cooling system prior to throwing more parts at the Van--
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Wildthings
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PostPosted: Sat Dec 05, 2009 11:55 pm    Post subject: Reply with quote

Did you compare your new thermostat to your old one? Do they have exactly the same shape? I wonder if your new thermostat is not fitting correctly in the housing and allowing bypass flow when it should not. Just a guess.

Have you had the water pump out? I have wondered whether it was possible to get so much erosion of the aluminium around the impeller that it would affect the pumps efficiency.

Do you have a rear heater? What happens if you close the valve on the heater?
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morymob
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PostPosted: Sun Dec 06, 2009 5:22 am    Post subject: Reply with quote

since u have a manual sw and u said it don't help at idle then what is your idle rpm's? I set mine per Bently and why don't u set yours up maybe 100-150 rpm more,might be too slow and make the diff in flow at idle.
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ftp2leta
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PostPosted: Sun Dec 06, 2009 6:33 am    Post subject: Reply with quote

I hate to say so but Special K may be right, in some ways.

First, you had 2 problem, the radiator was one.

I don't think your overheating, the fact that you light blink/temp rising on a 83.5 usualy mean that you have an electrical flaw.

Later van have 2 distinct system: a cooling level warning light and overheating gauge. On earlier van, the light is ONLY for low level coolant in the EX tank OR!!!! the light will also blink AND temp will rise if anything happen (cutting) to the coolant circuit, a faulty coolant level sender will also create the same problem. On later van, the light also as a second job, to flash is temps is to hight, NOT on earlier van.

Now, where is the problem! 3 main choice but 2 obvious, a faulty sender in the EX thank or/and a bad connection with the connector to this one.

In the junction box there is also a connector for the sender wire, wire is yellow and red, check those.

Image may have been reduced in size. Click image to view fullscreen.


Last and not the least, the cluster! It would be good to remove this one and check every little 6mm screw behind this one.

I'm not saying that it is you problem but begin by that.

Second, yes, get an infrared gun to make sure you are really overheating.

Other possibility I have seen, a bent hose, where! front of right head going to heater hoses.

The pump can be checked, remove all belt, 1 or 2 in your case and check water pump pulley for play. Look under the pump and find the wear alarm little hole, look for trace of coolant. It's a 1/8 little hole located under the pump in between pulley and engine mating surface.

BUT' i don't think it's the pump!

Last, i would change and blame the pump housing itself! yep!!! don't ask me how I know.

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If you need one, contact me in private. I don't give them free but sell them for cheap.

Good day
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vanagonforever
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PostPosted: Sun Dec 06, 2009 8:15 am    Post subject: Reply with quote

Thanks for all the great information guys. I especially appreciate those pictures! I'm going to spend some more time with it today and I'll report back. Thanks again!
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syncrosimon
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PostPosted: Mon Dec 07, 2009 2:05 am    Post subject: Reply with quote

Over here in the UK we have a product called Radweld, it is a sealant that you add to the coolant and it seals small leaks in the system. i am sure you have a similar product in the U.S. People who have used this product (usually to stop cylinder head leaks) have subsequently had many problems with overheating. It appears that the goo that is made by the product to seal leaks, also has a detrimental effect on the internal and complex flow around the engine. In particular the bleed pipes that run around the engine bay, and the other small link pipes that are there to try to remove air from the system.

It's just a thought, and you should be able to see this gloop in the smaller pipes if you dismantle, but it may be worth bearing this in mind.

Simon.
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vanagonforever
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PostPosted: Mon Dec 07, 2009 7:08 am    Post subject: Reply with quote

Well I still haven't convinced myself that I've got this problem nipped but I am leaning towards it being caused by the rough idle/electrical problems. After cleaning my grounds and the O2 sensor connector my engine started sounding a LOT better. It still isn't quite as smooth as I would like it to be but I'm making progress. Since I cleaned those few conections I have not see the same issue with the slow overheat at idle.

I'm going to use my Vanagon as my daily driver for the next several days and see if I can't get to the bottom of this mess. Thanks again for all of the help.
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Derek L
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PostPosted: Mon Dec 07, 2009 12:53 pm    Post subject: Reply with quote

Something I remember from my time working at a couple VW shops...

We would see instances where bad waterpump bearings have allowed the pump impeller to chew away the engine case and create a coolant bypass at low rpms. The offending pump may get replaced but if the installer doesn't fill the gouges in the case around the impeller then the van runs hot at idle due to lower flow. If the engine was coming out for a rebuild we'd weld and machine the area like new. In-car JB-Weld could be sculpted and filed to the proper shape to fill in the damaged area.

Not the most fun thing to check for but another to consider. Hope this helps!
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Terry Kay
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PostPosted: Tue Dec 08, 2009 1:45 pm    Post subject: Reply with quote

I don't think that cleaning the oxy sensor wiring would make the Van run any cooler from your explaination of the problem's in the first post.

And it's a big maybe on cleaning the grounds too.
Possible, but from what you said doubtful.

Did you remove the coolant level sensor and clean it up good?
CLR works very well for this job.

You hit the entire cooling system with the infared temp tool ?

This would tell you a bunch , real quick...

I wouldn't second guess the gauge reading until you do a couple of direct diagnosis discovery moves first.
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vanagonforever
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PostPosted: Tue Dec 08, 2009 6:11 pm    Post subject: Reply with quote

The temp level and expansion tank are both new. I installed them around July, drove about two thousand miles, and then parked my Vanagon around August until now. The temp sender unit in the thermostat housing was replaced a few months before that so I am confident in my gauge.

I'm not at all convinced I've fixed my problem either but I have improved my idle. I didn't mention that I was having other electrical problems that I also cleared up last weekend. Fuse 2 was blowing non-stop which caused not only my right tail light and marker light to stop working but it also stopped my left tail light, left marker light, right front corner light, and license plate lights from working. The problem was an oddly burned out bulb in my right marker light that was blackened and causing the whole mess. Once I replaced that bulb all was well. I doubt that impacted my idle but the fact that things that aren't supposed to be on fuse two were impacted by the rogue bulb made me wonder a bit.

Starting this past Monday the Vanagon is now my daily driver. I believe I've still got a subpar cooling system but after a fair bit of bumper to bumper gridlock in Baltimore this afternoon I am positive that I am far better off than I was a few months ago. I never made it over 3/4s on the gauge today but then again it was about 42 degrees outside so who knows. Most of the time I was pegged right in the center.

I'm starting to buy into this pump housing problem being the last of my issues. I think several things have been wrong given my steady improvements but something still isn't right and I haven't really messed with the pump/housing up to this point. In fact, next chance I get I'm going to crack open the housing, inspect the pump, and check the housing for any signs of damage. It may be a bit before I get around to it but I'm eager to see if I find anything.

Finally, I'd love to use an infrared sensor but I don't have one and doubt that I can afford one right now. I do believe that I am actually overheating though because when I really push things in my tests to see if my fan really isn't going to come on for example I can hear what sounds like boiling water in my coolant lines. Also, things just smell hot. The flow certainly seems blocked and it certainly seems to be causing major problems. Slowly but surely I'm figuring it out...
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PostPosted: Tue Dec 08, 2009 7:22 pm    Post subject: Reply with quote

Ok all you guys with no money Smile Even if I'm one right now, double Smile Smile

Ok, remember that, you all, here is the cheapest test in the world:

If you gauge is right and it's passing 3/4, poor some water on the head, it WILL boiled. The first rad fan speed kick at around 200F engine temperature (if your cooling system is in order), that is 94 or so in Celsius, why Celsius, well 100 is the boiling point, way more easy.

213F is 100C. Thermostat should open at 87C (189F), still, engine will rise at around 95C (203F) sometime. When all is in order of course.

Forget outside temps, that is BS, unless it's -40 outside Smile (do you get this one!!!)

I have an arsenal of testing machine, and I still use water when i have to carefully bleed a van that need serious bleeding....

So put some water there and wait. If it doesn't boiled your not overheating.

Choose the location where you put water carefully.

When i do big job like the last one i did (engine, cooling hose and line, rad), I use water on the head, yep.

Ben
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240Gordy
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PostPosted: Tue Dec 08, 2009 7:24 pm    Post subject: Reply with quote

but did you clean the coolant level sensor?

that is far far easier to do than pull the water pump off. If you pull the water pump you will have to refill your coolant and bleed it and so on, just a PITA if you don't have to.
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vanagonforever
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PostPosted: Tue Dec 08, 2009 8:01 pm    Post subject: Reply with quote

My understanding was that the blinking light can only come on at startup, if the coolant level sensor is unable to detect coolant, or if the temp sender is reporting a temp that registered at 7/8ths of the gauge. All of those parts are less than a couple of months old. They shouldn't need cleaning. Looking at my gauge and how it acts, I have no reason to think my sensors are bad. I certainly need to figure out my thermo switch controlling my fan - I bet I screwed it up when I added a manual override switch but I just don't know because I haven't really dug into it. I know it was working correctly before I added the manual override and it was a new switch so...

Correct me if I'm wrong though but if it was the pump housing then wouldn't my radiator remain cool enough to avoid triggering the fan? Would the entire system get hot at once? Wouldn't it be possible for only the engine bay to get hot while I idle (like when you have a closed thermostat)?

Thanks again everyone!
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PostPosted: Tue Dec 08, 2009 8:18 pm    Post subject: Reply with quote

my blinking light goes off after I wait a few seconds to start, then comes on steady once it warms up, even when the gauge is not showing it getting warm. I know for certain (yes by removing the cap and looking) that the tank is full of coolant. So it is certain that the sensor is not working correctly. I will take Terry's advice and clean the sensor, I think I have some CLR. There is some mucky stuff floating in the coolant, so I wouldn't be at all surprised if it is dirty enough not to function. I used the vacuum method to drain my coolant, so I am not surprised either that the grunge got dislodged and mixed with the coolant.
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