Real Engine Temperature

[moetheshmoe]

I've been searching the forums about all the "classic" Volvo heater core problems and it seems that there is never a temperature gauge warning when the heater leaks, overheats the engine and blows the head gasket. I did read that without coolant surrounding the sensor it won't go up in temperature and that makes sense. It also makes sense to install some other indicator of engine temperature that doesn't rely on coolant, so you can stop the engine before anything drastic happens. Does such an animal exist? And has it saved anyone's engine? Thanks.

[93Regina]

heater leaks, overheats the engine and blows the head gasket.

Hot engines are due to various reasons...when a redblock gets hot, it can take out the heater core.

Solution - Well, my 1984-244 came with a radiator, from somewhere, which had a temp sensor on it. With a 30-amp relay, one could grab the coil's hot-terminal, so when this sensor trips, that's all. Needless to say, one would have to find a higher set point.

Solution 2 - On top of fill tank, I drilled a hole, and inserted a threaded rod inside, with rubber washers on each side, along with flat washers, and two nuts. I used this as a ground, so a LED light was on all the time, when fluid was in reservoir. Problem is electrolysis happens on this rod, and it needs to be cleaned. In fourth post here, I might do it that way, if I did it again; it might reduce electrolysis.

Solution 3 - Watch your temp gauge; replaces hoses, and water pump at 50K miles.

[moetheshmoe]

Sounds like all good solutions but what about something that measures oil temp?

[moetheshmoe]

You know, now that I think about it, I really like your idea of a rod in the recovery reservoir. I'm assuming the coolant completed the circuit between the engine block and your led light? And no coolant - no circuit - no light. How about an aluminum rod so it wouldn't corrode(electrolysis)?

[moetheshmoe]

I'm going to reply to myself. I should do a little research before I open my big mouth. I guess oil temp units have been around for a long time. It just puzzles me that Volvo hasn't made them standard equipment but I guess that would be admitting their heaters are crap and that would open them up to a lot of litigation. While searching I did see a lot of after market temp monitors that attach to the cylinder head but they want about $150. I guess the best solution would be a coolant sensor/float in the recovery tank since that's the first thing that happens before the over heating.

[93Regina]

..rod in the recovery reservoir.

This VW coolant level sensor might work, along with its Expansion Tank: but I ain't got time to research this topic.

The problem I had with my setup was the full current of LED was traveling thru that rod and Electroplating was happening on that rod.

Using that setup for the Basement Water Indicator, not as much current would be traveling across coolant.

Of course, when light goes out, it means low water.

[moetheshmoe]

Thanks for the info. This VW setup looks cheap enough to give it a try. Thanks

[93Regina]

VW setup looks cheap enough

Check at your local salvage yards...I'm not an electronic geek, but at that forum, one could ask if there's a cheap way to have light/buzzer activate with low water.

A Guide to Purchasing 12 Volt LED's on eBay

[mika]

In the 850s, there is a low coolant indicator. If I am reading the above post correctly, the 240 does not?

[93Regina]

If I am reading the above post correctly, the 240 does not?

Negative...that's why water pump should be changed every 50K miles, and hose fitness should be checked.

On 940s with vacuum controlled heater valve, it should be changed out every 75K miles or so.