OK, the new-to-me 1990 240DL has lost about 2 quarts of coolant over the last 3 months and approximately 1000 miles. I have no spots on the driveway even if it is run for an extended period in place (now that the tail shaft bushing is replaced). I have checked the obvious suspects...no steam-cleaned spark plugs, no chocolate milk oil, no sign of coolant in the tranny fluid and the weep hole on the bottom of the water pump is dry. I have not noticed a coolant smell in the car and neither floor-board has a damp feeling (have not pulled carpet yet).

So what is your favorite guess for the phantom coolant leak? I can't check them until I get back from vacation but I am curious.

Car came to me with a new water pump and physically broken thermostat. I still have not fixed the temp compensating board but I "know" it is not overheating.

Thanks,

Mike

I found the issue...the thermostat housing is leaking in such a way that everything is evaporating before it could drip past the head-to block junction.

Mike

Pressure test it. Don't guess.

You don't have to get all fancy with a purpose-made tester, either, your brake bleeder or even a garden sprayer will suffice, as long as you have some means of watching the pressure.


--
Art Benstein near Baltimore

“The single biggest problem in communication is the illusion that it has taken place.” George Bernard Shaw

Hi Art.
That picture you used in the preceding response to illustrate a coolant pressure tester. I took one look at that and said to myself, "what the heck am I looking at?" I'd swear it was an ABS unit (the brake lines are fairly obvious), but it doesn't look like the one in my '93; and it's on the wrong side, if what I'm looking at really is the right (passenger side).
So please tell me -- is that some U.K. (right-hand driven) 240 that uses a slightly different ABS unit?
Thanks.
Ken

Hi Ken,

You gotta get out to the yards more often. :)

No, it is a run of the mill 92 940, once belonging to my MIL. I was testing the Nissens I'd just installed.




--
Art Benstein near Baltimore

The journey of a thousand miles begins with a broken fan belt and leaky tire.

Hi Art.
Thanks for getting back to me. You know, I've never seen the engine compartment of a 940 -- there aren't many pnp yards around here with them, or (sadly) with 240's, anymore.
But thanks!
Ken

On the passenger side of the engine, there is a horizontal metal pipe that seals into the back of the waterpump. If that seal is bad, or the end of the pipe is corroded you will get a slow leak that leaves nearly no evidence. The other area would be the two hoses that run from the back of the engine to the firewall under the intake manifold, these are a real pain to get to.

jorrell
--
92 245 307K miles, IPD'd to the hilt, 06 XC70, 00 Eclipse custom Turbo setup...currently taking names and kicking reputations!

I'll second the heater hoses through the firewall suggestion. Especially the one rubbing the auto trans dip stick tube. If you look at it when the engine is heated up to operating temperature you will probably see a very fine stream of coolant.
Dan

Jorrell,

Thanks for the response. The yahoo who did the water pump replacement probably did not know about the intricacies of installing one of these pumps (I have not done one in 10 years) so the leaking hard-line seal is a likely candidate. He did not replace all the bolts even though new ones came with the pump (found them in the trunk) which does not instill confidence.

I really hope it is not the heater core lines, but it would give me an excuse to remove the intake to install a new gasket before my turn at emissions testing rolls around next year. I am seriously considering it when I finally get around to doing the throttle-body and IAC cleaning (yeah, I know it should have been the second thing I did when I got the car).

Mike

Mike,

I have replaced the heater hoses with the intake in place, it is not a horrid job as long as you can "see" with your fingertips. Also note that you can replace the hard line seal at the waterpump by unbolting the pipe from the block, ie. no need to remove the pump and accessory belts. Inspect the pump end of the hard line for pin sized rust holes as well.

jorrell
--
92 245 307K miles, IPD'd to the hilt, 06 XC70, 00 Eclipse custom Turbo setup...currently taking names and kicking reputations!

Long time since I lurked or posted but I wanted to say...Jorrell was right. The moron who replaced the water pump before I bought the car attempted to re-use the seal on the hard line to the expected result (about a year later).

Since no one in town had a proper water pump with that seal on a Saturday when it catastrophically let go, I am running with a doubled up o-ring until a seal kit arrives.

Also, one of the two upper holes in the block for the pump is dead smooth inside which leads me to believe that:

a) This is actually an alignment pin hole less the pin or
b) They started drilling it to to an heli-coil or to tap it a siz larger and stopped

Thoughts?

Mike

All the holes in the block should be threaded for the pump--no "alignment" pins involved. -- Dave