Rear main seal or heads gasket? high temp!

fongo · 01-09-2009, 01:48 PM

Hi everyone.
Ok, so here's the problem.
I recently have been having surging high temp (all the way to the 270 reading!). It climbs shortly after 10 or 15 minutes running the car at idle. When I went for an oil change, the guys told me that I may have blown my heads, head gaskets or rear main seal, since the oil was coming out like chocolate milk! They said its most likely oil and coolant mixing as a result of the leak depressurizing the coolant system causing no circulation and hence no cooling. However after the oil change I looked under the car and didn't see any drippage.
How do I know which one is the problem? How do I effectively diagnose it? Can't make it to the shop because it starts to overheat 2 blocks away from my garage! I need to know because I'm planning to work on the car early spring.
Thanks!

USMC302 · 01-20-2009, 12:45 PM

The leak they are referring to is not external, it's an internal leak. You have a blown head gasket IMO.

jmdesales · 03-18-2009, 07:26 AM

If your car feels fine, coolant looks clean, no loss of oil level, exhaust normal, fan turns on after a few minutes and you changed temp sensor, and it reads way to the right hot, then you might want to try buying an economical temp gauge at autozone under 20 bucks, unplug stock gauge wire, connect new one to the temp sensor, and check the temp on the new gauge"you can just hold it in your hand", I was running super hot so i thought, the new gauge never went over 200, fan kicked in right at 200, where as the stock gauge read about "L" from NORMAL, near red when the fan would turn on, Bad gauge much better than blown head gasket. Stock mustang gauges are notorious for failing, I mean does your oil pressure gauge actually move, im working on a water temp, oil pressure, tach w/ light triple pod cause of this. Hope your as lucky as me and just have a bad gauge.

95 gt 5speed

bailey_57 · 03-24-2009, 07:51 PM

i agree, i've heard of guages crapping on foxes all the time. but given the milky oil, i would have to second the head gasket suggestion.

SlowGT · 04-03-2009, 12:30 PM

+1...another vote for a head gasket

01-09-2009, 01:48 PM	#1
fongo Registered Member Join Date: Jan 1999 Location: Farmingdale, NY Posts: 139	Rear main seal or heads gasket? high temp! Hi everyone. Ok, so here's the problem. I recently have been having surging high temp (all the way to the 270 reading!). It climbs shortly after 10 or 15 minutes running the car at idle. When I went for an oil change, the guys told me that I may have blown my heads, head gaskets or rear main seal, since the oil was coming out like chocolate milk! They said its most likely oil and coolant mixing as a result of the leak depressurizing the coolant system causing no circulation and hence no cooling. However after the oil change I looked under the car and didn't see any drippage. How do I know which one is the problem? How do I effectively diagnose it? Can't make it to the shop because it starts to overheat 2 blocks away from my garage! I need to know because I'm planning to work on the car early spring. Thanks! __________________ 1993 GT, MAC Fenderwell Cold Air Induction; Accel dist.,Splitfire plugs, BBK: 1 5/8 unequal length shorties, hi flow H-pipe w/ cats; Flowmasters 2 chamber American Thunder catback system, Motorsports 3-core radiator, 180º thermostat, BBK adj. clutch quad...the rest is bone stock!..but more mods to come!!

01-20-2009, 12:45 PM	#2
USMC302 Registered Member Join Date: Apr 2001 Location: Gallatin, Tn Posts: 1,326	Re: Rear main seal or heads gasket? high temp! The leak they are referring to is not external, it's an internal leak. You have a blown head gasket IMO. __________________

03-18-2009, 07:26 AM	#3
jmdesales Registered Member Join Date: Mar 2009 Posts: 2	Re: Rear main seal or heads gasket? high temp! If your car feels fine, coolant looks clean, no loss of oil level, exhaust normal, fan turns on after a few minutes and you changed temp sensor, and it reads way to the right hot, then you might want to try buying an economical temp gauge at autozone under 20 bucks, unplug stock gauge wire, connect new one to the temp sensor, and check the temp on the new gauge"you can just hold it in your hand", I was running super hot so i thought, the new gauge never went over 200, fan kicked in right at 200, where as the stock gauge read about "L" from NORMAL, near red when the fan would turn on, Bad gauge much better than blown head gasket. Stock mustang gauges are notorious for failing, I mean does your oil pressure gauge actually move, im working on a water temp, oil pressure, tach w/ light triple pod cause of this. Hope your as lucky as me and just have a bad gauge. 95 gt 5speed

03-24-2009, 07:51 PM	#4
bailey_57 Registered Member Join Date: Mar 2000 Location: Berwick,Pa Posts: 127	Re: Rear main seal or heads gasket? high temp! i agree, i've heard of guages crapping on foxes all the time. but given the milky oil, i would have to second the head gasket suggestion. __________________ '89 GT hatch back performer rpm intake, performer rpm cylinder heads, fms e-303 cam, kirban adj fp regulator, holley 65mm tb, harland sharp 1.6 roller rockers, alum driveshaft, 3.73 gears (283 rwhp, 303 rwtq new numbers with new heads)

04-03-2009, 12:30 PM	#5
SlowGT Registered Member Join Date: Jun 1999 Location: Columbia Co, PA Posts: 303	Re: Rear main seal or heads gasket? high temp! +1...another vote for a head gasket __________________ Old Slow GT New Slow GT--> under construction Latest Addition: 95 Cobra R, #73, bone stock, ~6100 miles.

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