washingtonkevin

1994 Mustang temp guage says hot but blowing cold air. Help please.


Here is the situation
1994 V6 Mustang with 140,000 miles.

Here is the symptom. The problem is intermittent for the last few weeks.

Temperature guage goes to the red line while blowing cold air from the dashboard vents. (Heater is set to hot on dash)
Then, it will start blowing hot air and guage will come back down to the N or Oin Normal.

The thermostat has been replaced and I had the coolant flushed at a shop this morning. (It was due an oil change so I had them do it)
The oil and coolant show no signs of mixing.

The temp sensor and the fan relay (ccrm module)and the fan are all working normally.

What is the problem? Radiator blocked? (I would thought that would have showed up at the shop this morning during the flush)

Which hoses to/from the radiator should have pressure in them when I grab them? Can a hose delaminate on the inside and create a blockage?

I would like to figure out what is wrong with this without just throwing money away that does not need to be. Any ideas would be appreciated.

Kevin

raz54

The system probably has rust breaking loose blocking the flow. I flushed my Nova's system once and it started doing the same thing. I had to flush it about 6 more times before all the crud was out.

mustangman02232

whats the oil look like?

Derf00

Check that the heater control valve is actually working/connected. This is the valve that turns the water on and off to your heater core. If that's disconnectedor loose/sticking that would cause intermittent problems with getting heat into the car. It's under the dash on the passenger side on older cars. I believe if you follow your heater hose lines to the fire wall, one of those connections is directly on the heater control valve. If not then it's connected near the engine as the line comes out of the engine and goes to the firewall.

RyansQuick6

^^^^ +++1Check your sensor as well, I believe the fans have a seperate one that may be functioning properly, but the dash sender may be defective intermitently.

Also check your fluid level constantly as those years tend to have slow head gasket leaks due to a poor design. If that is the problem use the head gaskets off the newer 3.8's.

Ryan

97tunedmustang

I also had this exact same thing your describinghappen to my 97 some time ago, and it was a blown head gasket with a slow leakthatwas pressurizing the coolant system and causing itto do just as your describing.

bds95stang

most likely a head gasket, mine did the same thing and it was the head gasket

cobra232

sorry dude your wrong.

he has a 94

it is head gaskets that are blown. those are the classic symptoms of a common problem with 94-early 96 engines.

2 ways to fix the problem
1 take the heads off and and heave them checked for warpage and resurfaced as needed. then get a set of FORD BRAND ONLY MLS head gaskets (Multilayer steel) for 1999+ 3.8 models and use 1994 new felpro or TRW head bolts. this will elimintate this problem from ever happening again

or
get a 97-04 3.8 engine from a junkyard and put it in. 97 and 98 engines will pretty much just drop right in and plug the wireing harness back in and drive. the 99+'s are called splitport head engines and have more power but need a modified fuel rail for your 1994 fuel system available from www.rpm-mustangs.com

many places sell 3.8 engines.

www.mpsautosalvage.com has any year engine and so does http://stores.ebay.com/Bob-Cossells-Mustang

$300-$500 is average price for a 1997 or 1998 engine and that is what i reccomend instead of doing the headgaskets on your engine as it will be cheaper to drop the newer engine in.

Bob Cossels has an EBAY store they are in West alexander PA not too far from me and are reasonably priced as are MPS autosalvage out if Windber GA

2001 3.8 engine $325+ shipping and 01-04 blocks are the strongest
http://cgi.ebay.com/ebaymotors/USED-...3430QQtcZphoto

mustangman02232

just to add, or, you can get a 4.2 v6 out of an f150 as well