Volvo Repair: Head Gasket/Engine Issues, temperature guage, radiator repairs

Question
I have a '94 940 Turbo with a re-used engine placed in the car at around 100K miles; the car now has 207K miles.  Recently, my car just stalled and stopped in my driveway.  I've really tried to maintain this car well and the maintenance has been performed by Volvo mechanic types. The next day it started ok, drove it around all day -- no problem; a day later it cranked up, but didn't start -- had it towed to a repair guy who specializes in Volvos (he's not the same guy who put in my re-used engine) and he's done ok with me.  This repair guy replaced the fuel pump relay, ignition module, did his computer diagnostic test and claimed he drove the car around a bit and that the car was fine. My daughter drives the car from the shop; on the interstate for 5 miles and then in "city" traffic and we have lunch; smoke starts coming from the hood -- and I'm thinking maybe the mechanic spilled some fluids under the hood; I'm driving behind my daughter and I think smoke is coming from the exhaust -- the check engine light comes up and then the car dies on her on a heavy trafficked road.  We tow the car back to the repair shop -- after towing the car back to the shop, our mechanic claims no major problem with the engine but the radiator is cracked.  Of course, I'm very suprised by this -- he claims "stuff happens" -- he has a good reputation in the area and he's been square with me over the years.  Well, I authorize the radiator repairs at around $678 (in addition to the earlier repairs of $475); he tells me he's fixed the problem -- test drove it a bit and though the neddle for the temperature guage gets stuck in the middle when he drives the car -- he proclaims it a fit and repaired car.  We go back and pick the car up -- daughter drives it for 8 miles, parks the car for around 15 minutes; the car is now leaking coolant when she starts the car; she drives it another 5 miles to the house where it still starts but I check under the hood and the coolant is leaking from a hose.  Car gets towed back to mechanic; he replaces the hose; says he'll run a sealant that might seal any hairline cracks causing the problem; this, of course, infuriates me -- I've lost complete confidence in his ability to diagnose or fix this problem; he later tells me it could be a head gasket problem, but he can't know unless he takes things apart!  He claims that something is pushing the coolant out of the system when the engine is turned off.

I've had it with this guy; I suspect that when he did the original repair work he tripped up something that caused the radiator problem which was compounded by our driving the car.  I plan on taking it to the other mechanic in the area (he's the one who replaced the engine but he's not conveniently located) to get a sense of the problem.  This is my run-about car which I use to commute on the interstate to work (80 miles a day) and I was planning on turning it over to my daughter.  What do you think of this mess?  And what do you think is the mechanical problem. thanks  

Answer
Chris, There are a lot of different part to the cooling system. Sounds like this guy is a moron.  It doesnt take a rocket scientist to diagnose a cooling system problem.  Sealant is a definate no-no.  I would flush that junk out of there.  I wish I could see the car but the only way to ween out a leak it to pressure test the system.  Sorry I couldnt help more.  Roger