TheSamba.com :: View topic

Fri Oct 13, 2023 2:36 pm

So I replaced the entire cooling system (pipes, hoses, plastic bits). Prior to the work everything was fine.

I burped the system with the front wheels on ramps, with bong (used the old upper rad hose). Bleed the system at 2k RPM, until there were no bubbles anywhere. The temp gauge stayed normal, and the low speed fan cycled on and off (jumpered fan has 2 speeds, new resister).

All seems great. However, after putting on the pressure cap the temp gauge goes high and the fan doesn't turn on. Bleeding the rad shows no bubbles. It acts like the thermostat is stuck, (it's installed the correct direction). Rad gets warm, but not hot.

Any suggestions?

Fri Oct 13, 2023 2:51 pm

Check compression tank temp when gauge shows hot.

Is it totally full?

If the temp on the compression tank is showing higher than normal — which for me is 160-170 on a hot day — the thermostat concept is interesting.

But lesson learning here, possibly... I put any I have on the stove in heating water before install, to confirm they indeed open at 80C or 87C depending on which one it is (I only buy 80, 87 is mostly for really cold climates).

The thermostat should be marked on the rim as either 80 or 87.

If you’re showing full-hot but the compression tank isn’t, I’d bet a farm (photo) that the blue cap is venting too early and/or the tank isn’t fully full.

Fri Oct 13, 2023 3:00 pm

I did exactly the same thing last year. Before, my temp gauge was normally just below the LED. After the switch of all the components, the needle stayed just above the LED with the system at the same temp. The difference was the temp sensor at the t-stat housing had a different resistance.

Is your van not over heating but the needle runs a bit higher than before? The real test is to get an IR gun and read the temps. The issue could just be at the gauge and sensor and not in the operation of the system.

Fri Oct 13, 2023 3:07 pm

I’m a firm believer, too — at least for me — there’s always a little bit of air getting temporarily trapped along the 35 feet or so of Coolant Highway these things have in total travel.

My overflow tank normally takes quite a few miles and/or heating-cooling cycles to rid the last bubbles, and show the same level in the overflow morning after morning. The rear heater is probably the biggest trap.

Fri Oct 13, 2023 4:48 pm

Thanks for the advice. I check the thermostat, re-fill/burp and thermal cycle the system. I also ordered all 3 new temp sensors, as "belt & spenders".

As for the gauge. I've replaced the voltage regulator and cleaned the contacts on the sender and instrument panel (gauge stopping working). I've seen the post about using resisters to see if the gauge is operating properly, but it doesn't say anything about calibrating it. Is there a DIY guide to make guage variable resister setup like the GoWesty one? It's on back order due to supply chain issues, so it will be awhile. I want the gauge to work so the GW over temp alarm will work properly.

I'm also am getting one of these dual gauges (for oil pressure and coolant temperature).

Fri Oct 13, 2023 4:54 pm

You’re welcome... and that gauge is awesome!