EX overheats! How accurate is coolant contamination test??

[wcraycroft]

Just towed my 95 Ex to a dealer. Does anyone know how reliable the chemical test for coolant contamination by exhaust is??? My 95 EX started overheating almost immediately after startup. Coolant was low, so I topped it up per the service manual, getting the air out as best I could. But I couldn't feel gushing warm water on the top radiator hose. Still overheated, so suspected thermostat, pump, head gaskets, or worse. No white steam or other glaring indication of blown gasket, no coolant on the dipstick. Towed it to a dealer service dept. The service rep phoned and said that they did a chemical check on the coolant for exhaust contamination (NO2) and the test came back positive. He said that this indicates a blown head gasket at the least. On the basis of this test, and the 120,000 miles on engine, they are recommending replacing the engine for $4,000!!!. Their rationale is that it will cost me $1000 just to take the heads off and replace the head gasket, and if heads are warped, it goes up to $2000. So instead of spending $2000 to rebuild top of engine, let's spend $4,000 for a complete rebuild. All of this based on a chemical test on coolant that I never heard of before (except for diesel engines, where the test is done to determine if coolant needs replacing, not engine). They claim that they tested the thermostat, but I'm heading back there now to see for myself. My question is how reliable are these chemical tests? Could they give false positives? This service rep could be trying to save me money on a hopeless engine, or could be pumping up his commissions. Can anyone tell me about this test?? Thanks!

 

[marragtop]

I'm not familiar with the test, but I'd start with replacing the thermostat. If it overheats that quickly, it sounds like the t-stat is stuck closed.

 

[JDraper]

The CO test is an indicator of possible problems, not something to determine if the engine needs to be torn apart. Besides the CO test, they should also do a pressure leakdown test and a compression test.

If the dealer is suggesting you put a new motor in based soley on the CO test, take the truck somewhere else.

Where do they get $1000 more if the head is warped? You can get remanufactured heads much cheaper than that, and if it's not warped too far, you can have it planed flat a LOT cheaper. Check out http://www.headsonly.com/ford.htm . They have a remanufactured head for the 4.0 OHV motor for $175.00

 

[wcraycroft]

Ran test again -- came up negative!

Thanks for the posts. All good advice, especially not relying on this test alone. I went to the dealer to see for myself. They ran the chemical test on the coolant and ... this time it came up negative! So I asked them to pop in a new thermostat, and, you guessed it -- no more overheating. I boiled the old one and it didn't budge. BTW, lots of good posts about overheating problems in this forum. And the advice is always the same -- go for the thermostat first. Thanks, again.

 

[ExplorerDMB]

Glad your problem was fixed. Ford dealerships have gone down hill in my opinion.

-Drew