TheSamba.com :: View topic - Cooling system question 1991 2.1

Mon May 23, 2016 2:39 pm

Hey all. Just got back from a trip from San Juan island and of course my 1991 westfalia is giving me a hard time! I was driving around and noticed that my temp gauge was at the second last line and the led indicator was blinking... Thinking that engine was too hot I tried dropping a couple drops of water on the heads to see if they boil and of course they did. I've noticed that the temp really starts to increase, light flashes, when going slow or at idle. It sits just above the LED at highway speeds. Turning the rear heater on decreases the temperature to lower part of led. I did not hear the fan turn on when it was too warm, but have read that the fan really shouldn't come on too often during normal operation? On my last trip I was broke down with a bad water pump so got that professionally installed while at my destination. I also replaced the pressure cap. Also there is a tad bit of air in the top of the pressurized tank. Normal? Can anyone provide any insight as to what I should be looking into? Cheers!

Mon May 23, 2016 3:08 pm

Does your fan come on at all when you're at idle or going slow? The fact that you overheat under those conditions, but not at highway speeds, suggests that your cooling system is working as long as air is flowing over your radiator. When the van is slow or idling you're not getting enough airflow - and that's when the fan is supposed to kick in.

Search for the method to jump the wires that attach to your temperature switch to trigger the fan (the switch at the bottom driver's side of your radiator). If that doesn't make your fan spin than you know there's some problem between the switch and the fan, or the fan itself. The switch might be bad too.

How much air is in your pressurized tank? It should be full. If it gets too low that should trigger your LED light.

Mon May 23, 2016 3:23 pm

samander wrote: I did not hear the fan turn on when it was too warm...

^That's a red flag to me. If the fan is not turning on, there's a problem (faulty fan switch, air bubble in the system that needs burping out, faulty fan motor, etc.).

samander wrote: ...but have read that the fan really shouldn't come on too often during normal operation?

It should turn on any time the coolant in the radiator reaches the specified temperature of the fan switch, and that can be even just after the engine is shut off, let alone driving in slow traffic. Sitting in a drive-thru line, my '90's fan will cycle on/off multiple times.

samander wrote: Also there is a tad bit of air in the top of the pressurized tank. Normal?

I fill my '90's brim full and after bleeding the system the level drops about an inch or so and stays there.

Mon May 23, 2016 3:42 pm

Thanks guys! It's factory ac model as well but not working. Alright so I jumped the two wires from plug at lower drivers side and got both the low and high speed fans running. They are quite loud! What could this indicate knowing that engine is definitely running too hot? Right before I bought it the thermostat was replaced as well

Mon May 23, 2016 3:59 pm

Fan switches go bad and need to be replaced every five years or so. Thermostats are known to be bad right out of the box and radiators are known for clogging with age. Pressure caps can also be an issue.

Mon May 23, 2016 4:00 pm

Also, I am currently idling I'm driveway and needle is above led with heads also bubbling with water. The rad still feels cool with no fan on. Defective thermostat??

Mon May 23, 2016 4:31 pm

samander wrote: Also, I am currently idling I'm driveway and needle is above led with heads also bubbling with water. The rad still feels cool with no fan on. Defective thermostat??

Could be. And perhaps air in the cooling system.

A good plan is replace the thermostat and bleed the air from the system. And while you are there..replace the radiator fan switch.

How old is your radiator?? If it is original..could be plugged..and give you the same cold radiator hoses like a bad thermostat.

A good test..once you are certain there is no air in the cooling system and the radiator thermo fan switch is working..is to turn your heaters on and if the coolant temps drop..the radiator is suspect.

Mon May 23, 2016 4:35 pm

Put the thermostat into boiling water, what happens?

Mon May 23, 2016 5:29 pm

I put it in boiling water and it wouldn't start opening until after 190. Is that normal?

Mon May 23, 2016 5:35 pm

samander wrote: I put it in boiling water and it wouldn't start opening until after 190. Is that normal?

For a high temperature thermostat yes, but your engine would have come with a lower temperature thermostat.

Mon May 23, 2016 5:39 pm

samander wrote: I put it in boiling water and it wouldn't start opening until after 190. Is that normal?

The temp rating on the thermostat is the OPENING temperature. It would be fully open about 10* higher than the rating.

So if your thermostat is marked as 87*C..the thermostat opening would start at 188*F ..about what you saw when you tested it.

Mon May 23, 2016 5:41 pm

If you really want to play Sherlock Holmes on the cooling system, have a bunch of fun.

Or-- replace the radiator and the temp running hot will be nothing but a memory.

The radiator is pugged in the coils surrounding the fan switch.
It never signals the fan to kick on.

The rear heater cooling it down should have instantly told you this in your primary investigation.

Mon May 23, 2016 6:18 pm

Thanks guys. I'm getting the feeling that it's the rad. Even with the new thermostat and switch I can't get the thing to cool properly or haven't heard the fan come on. Better be smart and just order one. Is there a certain brand I should look for/where is the best place to get one online? I'm up in Canada if that helps.

Mon May 23, 2016 6:39 pm

samander wrote: Thanks guys. I'm getting the feeling that it's the rad. Even with the new thermostat and switch I can't get the thing to cool properly or haven't heard the fan come on. Better be smart and just order one. Is there a certain brand I should look for/where is the best place to get one online? I'm up in Canada if that helps.

One of our on-line vendors VC, has a Behr radiator for $170USD $223CDhttp://www.van-cafe.com/home/van/page_312_906/radiator-p312.html

They fit well and are (last time I fitted one) a drop in fit.

I know Canadian customs will eat some duty fees..and delay the shipment. So much for the NAFTA treaty..don't get me started.

Amazon.ca looks like they have $265CD Nissens..which requires some mods to fit according to the description and other's experience here. https://www.amazon.ca/AutoPartsWAY-Canada-1984-199...n+radiator

I would try and get the Behr if you can.

Mon May 23, 2016 6:49 pm

Wildthings wrote: Fan switches go bad and need to be replaced every five years or so. ...

Replace it with the lower temperature switch.
http://www.busdepot.com/25195948175

Aloha
tp

Mon May 23, 2016 7:08 pm

I think I will order this guy here. Makes the most sense and its on sale
https://www.cip1.ca/ProductDetails.asp?ProductCode=VWC%2D068%2D121%2D253%2DE

Mon May 23, 2016 7:24 pm

Tom Powell wrote: Wildthings wrote: Fan switches go bad and need to be replaced every five years or so. ...

Replace it with the lower temperature switch.
http://www.busdepot.com/25195948175

Aloha
tp

That is the switch I have run for 20+ years at this point, but some people don't like it because it will cause the A/C to kick off when the high temperature contacts close. If he has a 195* thermostat the stock fan switch will work well enough.

Mon May 23, 2016 8:50 pm

Well its ordered! I will keep you all posted on the outcome. That low temp sensor is something I will consider for sure.

Mon May 23, 2016 8:55 pm

Wildthings wrote: Tom Powell wrote: Wildthings wrote: Fan switches go bad and need to be replaced every five years or so. ...

Replace it with the lower temperature switch.
http://www.busdepot.com/25195948175

Aloha
tp

That is the switch I have run for 20+ years at this point, but some people don't like it because it will cause the A/C to kick off when the high temperature contacts close. If he has a 195* thermostat the stock fan switch will work well enough.

Wild,
Couldn't you use a binary AC switch instead of a trinary switch with the lower temp fan switch to keep the AC pump cycling?

Mon May 23, 2016 9:00 pm

insyncro wrote: Wild,
Couldn't you use a binary AC switch instead of a trinary switch with the lower temp fan switch to keep the AC pump cycling?

It would be better to just alter the wiring for the A/C so that the A/C didn't cut off when the fan kicked into high speed.