B20 thermostat 92c

[arcturus]

Hi, I am would like to obtain a replacement 92c thermostat for B20b . I could send of to VP in Sweden and pay double the price for one with shipping or alternatively replace with a similar 'stat from perhaps another make of car locally which uses the same.I recollect someone saying that some land rovers used a similar one. any thoughts on this? can't find one here in Portugal

[142 Guy]

Compared to where I live, everyplace in Portugal is close to the ocean. Are you reasonably close to any Penta marine dealers? They might be able to supply you with a correct fitting thermostat.

[Derek UK]

Are you sure you want a 92º? 77 or 82 are standard but there is an 87 listed. I would try a main dealer, they can order one in as part of the spares system and you shouldn't have to pay for delivery. Any alternative thermostat must have the plunger underneath to block of the bypass tube. Many that are listed for the B18/20 don't have that.

[142 Guy]

Check out BorgWarner - 402282D (82C) and Motorad. Motorad has a whole bunch of thermostats with different temperature options and they all have the jiggle valve and the by pass shut off disc.

You may be able to find a local parts vendor who can source the Motorad or BW parts.

[Clan]

Originally Posted by Derek UK

Are you sure you want a 92º? 77 or 82 are standard but there is an 87 listed. I would try a main dealer, they can order one in as part of the spares system and you shouldn't have to pay for delivery. Any alternative thermostat must have the plunger underneath to block of the bypass tube. Many that are listed for the B18/20 don't have that.

92 is specified, it is part of what gives the cars such a good heater. You may think a few degrees makes little difference but in Practice it makes a big difference.

[arcturus]

Hi, a friend of mine is sourcing an 88c Mahle for me. The reason I'm looking to change is that the needle barely gets out of the "cold" section of the gauge, even in the current hot weather here. Only time it does that is if I'm standing with the engine running.Tested 'stat and it's fully operational.

[142 Guy]

Originally Posted by arcturus

Hi, a friend of mine is sourcing an 88c Mahle for me. The reason I'm looking to change is that the needle barely gets out of the "cold" section of the gauge, even in the current hot weather here. Only time it does that is if I'm standing with the engine running.Tested 'stat and it's fully operational.

That would be pretty strange. If you have the later design with the expansion tank have you checked to see if the level is still at the bottom
which would jive with a low coolant temperature? Have you done the dash gauge test as described in the service manual or have you checked the actual top of rad temperature with a thermometer? I am more inclined to believe that you might have a gauge or voltage stabilizer problem.

It has been bumping into the 30 - 36 C range here lately and parked at a stop light the electric fan is on in a flash and the coolant temperature is in the 92 C+ range. I have a thermostat which starts opening at 83C and is fully open at 90C. Is 88 C the fully open temperature or the start of opening temperature? If 88C is the start of opening temperature you may find yourself burping coolant when stopped and idling.

[arcturus]

Hi, really can't answer your questions. I have tried two separate 'stats and they gave the same results. Just fitted the 88c but haven't had a chance to test it,will report back. When stationary the needle will creep up to the higher end of the gauge and then the electric fan kicks in.
BTW fitted Quinton Hazell.. QTH135K replacement
A schematic of how the 'stat works in the head would be usefull

[142 Guy]

If you have tried two different thermostats and your getting the same results I am thinking that the problem may be someplace else.

If you disconnect the gauge sensor lead from the sensor and connect a 10 ohm resistor between the wire and ground the dash gauge should read around 100 C which is the dividing line between the green and red areas on the early 140 cluster. If that works then the gauge and stabilizer are probably OK. Check the resistance of the sensor. At 30 C it should be around 170 ohms, at 25 C it should be about 210 ohms and at 20 C about 270 ohms. These are all estimated using the Steinhart - Hart equation so will not be super accurate.

If you check the cooling section of the green book service manual you will find a diagram showing the cooling system and an explanation of the by pass valve operation.

[arcturus]

Don't have green book. With new stat 88c gauge goes to middle and beyond. haven't had a chance to give extended run. Don't suppose that you could post a copy of the by pass?