Hi, I was hoping you could offer some advice for a dilemma I've come across; Here are my two main questions (and I'll describe the scenario it relates to below):
1) Can the 'check engine' light be triggered directly by high engine temperature? (ie is there a temperature sensor that would turn on the CEL due to engine overheating?)

2) If the engine is overheating due to lack of coolant, will the Engine Coolant Sensor pick that up, or will it not operate because there is, in fact, no coolant to measure the temperature of?

And here's my situation:
I was checking out an '89 240 DL when the owner mentioned that the temperature gauge seems to be broken- and sure enough, for the first ~10 min of idling the thing doesn't even budge. However, a minute or two before I put it into gear to start the test drive, temp gauge begins climbing; and by the time I'm a quarter mile out it's reached around 3/4 the way up. I turn the car around to head back and the temperature starts to fall a bit, but never below half way. Once we get back I check the coolant expansion tank (probably should've done that first) and lo and behold it's bone-dry. Engine Oil looks good (clear, no signs of sludge) so I head out to buy some coolant, fill up the expansion tank (takes about a gallon), and give it another test drive. This time the gauge responds quickly after ignition, and gently climbs to about a quarter of the way up where it stays for the remaining mile or two of the test drive.
So here's the dilemma- I really like this car (low mileage, single owner, engine seems to run great, practically rust free- really clean...) but I'm worried that the owner has been driving around with no coolant thinking that his temperature gauge is broken.

He says he's only driven it a few times since it was last serviced (6/2013) and the check engine light never came on since then- if that's true, would it imply that the engine temperature never got into the 'red'? (cause otherwise that would've triggered the CEL?) And if there is a temperature sensor that triggers the Check Engine Light, does it rely on coolant temperature and therefore wouldn't work in the situation of over-heating due to lack of coolant(hence my two 'main questions').

I love this car - manual , runs smoothly, looks almost mint condition... but the owner is charging accordingly (six grand), which would be a lot to pay for a warped engine block.

What are your thoughts on the matter? I'd appreciate the advice,
Joshu

 

Owner is a cretin to drive a car that needs a gallon of coolant!
Who knows if the car was overheated? Must check that further...
Six grand is way too much for a car with such history of neglect.
CEL should not trigger under these conditions, yet overheating like that, who knows... Hard to tell what else is going on.

 

Top off coolant, run engine, see if overheats. You will know if it boils over!

Flaky temp gauge means bad compensator board in cluster. Give the dash a good smack and see if any change. Could be bad wire at cyl head too. Its yellow and goes to single prong sensor under intake Mani.

If its a 245 maybe...if its 244, no way! Pics!!!

 

That's bonkers money for that car. I get it, but for my money and my area I just saw a 91-92 240 DL in the wealthy area of Connecticut that looks like a California car with just over 100k miles original owner, etc. for $2k... Except she won't sell it anymore and I don't blame her, neither would I, but her price was very reasonable.

See if you can rent a "Block Test" kit from your local auto parts chain. Here it's AutoZone, you buy this blue fluid, put it into the tester, and on a cold motor suck air from the coolant in through the fluid, it's simple to use. It will test to see if any combustion gasses have gotten into the coolant from a failing head gasket, or warped head, it's not always coolant going into the combustion but the other way round with some redblock cars. Pressure can build in the coolant, heat pushes out said coolant, heater cores can go, hoses etc., ask me how I know....

If it was me, I'd sigh and walk away or at least have it taken through by a very qualified volvo specialist if you're really considering buying it and the bug has gotten you bit hard.

They are getting older and harder to find, but I'd be very cautious on this one. And that price...ouch

 

Hey, thanks for the replies- and yeah, I was pretty surprised when I saw the dry bottom of that coolant expansion tank...can't believe this guy didn't connect the 'broken' temp gauge with checking the coolant level. For the last few years I've had a beat-up '90 240 dl that I inherited from my brother, who himself inherited it from my dad- the rust was bad enough that I'm always nervous at the prospect of jacking it up to work on it (eg changing out tie rods and ball joints). So the dream is to have a 'fresh start' that I could keep going as long as possible- this '89 really looked the part, but at the moment I'm thinking you guys might be right- it's a lot of money for a vehicle with such a dubious history...

And thanks for the 'block test' suggestion- I'm not sure the owner will be keen on letting me fiddle with his car much, but if I decide to pursue this car and the test is quick and easy that may be the way to go- I'll check it out.

Thanks for the advice- for now the search continues...