1989 beaver Marquis wax valve

[Sigbert]

On a 1989 beaver Marquis with Detroit 6v93 where is location of wax valve that controls fan speed . Had four electric fans added because mechanic couldn't get fan to work after installing new steering pump and fan drive and I want to try and fix, thanks Sigbert All

[vito.a]

It will be in the metal portion of the radiator hose that returns hot coolant to the radiator. 

[jacwjames]

My thermovalve is mounted on the radiator, top, rear. 

You should be able to trace the lines from the switching valve back to the thermovalve.

When I was having trouble with mine it was running wide open.  Contacted Monaco and they had me do two tests that tests the motor.

1. I plugged both lines and the fan ran wide open. 

2. I then put a union in between both hoses and the fan ran at an idle.

Based on the above they said it was probably the thermovalve which I replaced and it fixed the problem.  I did take my old one apart and I found a small piece of cloth in it, I just had the rig into a Cummins shop to replace the radiator, they must have wrapped the thermovalve in a rag while doing the switch over. 

I purchased the thermovalve from Whitehouse Products in the UK, quite a bit cheaper then buying in USA.  https://www.whitehouseproductsltd.com/products/hydraulic-motors/hyd-gear-motors-fan-valves/dynamatic-fan-drive-motors-valves/553-1-09857-210-thermo?returnurl=/SearchResults&s=553/1/09857/210&pn=1&ps=24&lm=grid_template&b=true#jump

You will have to create an account to see the price but I found it was worth the effort, cheaper and took ~1 week to get it. 

NW RV Supply does carry them https://www.nwrvsupply.com/?s=wax+&post_type=product&type_aws=true

Mine was this one https://www.nwrvsupply.com/product/ax-valve-553-1-09857-210/

 

 

 

Edited June 19, 2023 by jacwjames

[Sigbert]

Thanks for the help when I get home next week I'll check it out I still have fan blade. I spent over thirty thousand on repairs and couldn't get fan going, electric fans done failed twice haven't drove hundred miles since it broke down last year when pump went out

[timaz996]

My thermal valve or “wax valve“ is mounted in the radiator tank at the rear lower portion of the radiator. It is completely hydraulic and no electrical wires going to it. Two 4 inch hydraulic hoses go to the hydraulic fan motor. You can test your wax valve the same way that Jim stated above. If it is the wax valve you can buy it from a place in Britain called white hydraulics I believe for less than half the price of what everyone else wants here in the US.

[Paul J A]

21 hours ago, Sigbert said:

Thanks for the help when I get home next week I'll check it out I still have fan blade. I spent over thirty thousand on repairs and couldn't get fan going, electric fans done failed twice haven't drove hundred miles since it broke down last year when pump went out

Please consider TALKING to the guys at; https://sourcerv.com/    

 

[Frank Bergamo]

It’s possible there is no wax valve, fan electronically controlled. Might be the reason can’t locate thermo valve, there isn’t one. As stated above, Source Engineering is the go to for this system. Give them a call. Hope this helps.