1998 Ford Mustang Gt, Oil(mixed with coolant) flowing out of the coolant resivior.

Calhuff

New Member
Jan 24, 2019
3
0
1
17
Maricopa Az 85138
1998 Ford Mustang GT (startup after 9 years) The engine started right up, and as I watched the engine after it had started, Light brown oil (obviously mixed with coolant) started to flow very quickly out of my resivoir. Also, I found that the oil and coolant mix was found everywhere in the cooling system including the thermostat, but it was not in the oil pan when i drained it. after doing research, most people said it was the head gasket. I found that difficult to believe because of how fast the oil was spewing out of my coolant resivoir. further research told me it could be the oil cooler gasket... I took the oil cooler out (water and oil mixed were inside the oil cooler) but the adapter gasket was in perfect condition. No faults or anything. I decided to test my oil cooler by sealing one side off to a block of wood, and putting the water in where the coolant would usually go. I did this and water began to flow out of the oil cooler where the oil filter would be if it was connected. Is that suppose to happen? Is it possible for there to be a fault or internat crack inside the oil cooler allowing them to mix? are there aftermarket solutions or do i pay $400 for a brand new oil cooler?
 
  • Sponsors(?)


Azazel6221

Member
Jan 24, 2019
11
2
13
40
Scranton
1998 Ford Mustang GT (startup after 9 years) The engine started right up, and as I watched the engine after it had started, Light brown oil (obviously mixed with coolant) started to flow very quickly out of my resivoir. Also, I found that the oil and coolant mix was found everywhere in the cooling system including the thermostat, but it was not in the oil pan when i drained it. after doing research, most people said it was the head gasket. I found that difficult to believe because of how fast the oil was spewing out of my coolant resivoir. further research told me it could be the oil cooler gasket... I took the oil cooler out (water and oil mixed were inside the oil cooler) but the adapter gasket was in perfect condition. No faults or anything. I decided to test my oil cooler by sealing one side off to a block of wood, and putting the water in where the coolant would usually go. I did this and water began to flow out of the oil cooler where the oil filter would be if it was connected. Is that suppose to happen? Is it possible for there to be a fault or internat crack inside the oil cooler allowing them to mix? are there aftermarket solutions or do i pay $400 for a brand new oil cooler?

I just had this problem with a different vehicle your oil cooler went get a new one its pumping the oil into the coolant system thats why its not in the motor
 
  • Like
Reactions: Calhuff

2006FlatBlack

New Member
Dec 3, 2019
3
0
1
54
91001
I'm having same problem with a 1998 3.8 manual transmission. The $400 oil cooler mentioned, is it motor oil cooler? Where is that located?

Thanks.
 

tsemmett

Active Member
Jul 2, 2019
207
29
38
37
US
I'm not sure a 98 3.8 has an oil cooler (I had a 91 3.8 that did not). Head gaskets are a common point of failure with the 3.8 though; I'd be testing for that (leakdown for instance).
 

2006FlatBlack

New Member
Dec 3, 2019
3
0
1
54
91001
I checked yesterday and there is no oil cooler. I did compression test and all 6 came in between 150-160. I also did a pressure test on cooling system and it does not lose pressure. I read on another search that it could be the timing chain cover?
 

tsemmett

Active Member
Jul 2, 2019
207
29
38
37
US
Timing cover could make sense; the water pump passages go through it, like a small block. Intake manifold could also make sense (coolant flows through it, and a leak could drop coolant in the valley to drain down into the oil pan). I would think if either of these were leaking, you would lose pressure on a pressure test though.
 

Pepe 98v6

New Member
Mar 29, 2020
3
0
1
21
Virginia
Timing cover could make sense; the water pump passages go through it, like a small block. Intake manifold could also make sense (coolant flows through it, and a leak could drop coolant in the valley to drain down into the oil pan). I would think if either of these were leaking, you would lose pressure on a pressure test though.
It can’t be either because we’re talking about oil in the coolant tank but no coolant in the oil. Anybody have anything else I can check?
 

STEVE PATTON

I smell a conspiracy
Jan 6, 2019
193
97
38
70
ohio
1998 Ford Mustang GT (startup after 9 years) The engine started right up, and as I watched the engine after it had started, Light brown oil (obviously mixed with coolant) started to flow very quickly out of my resivoir. Also, I found that the oil and coolant mix was found everywhere in the cooling system including the thermostat, but it was not in the oil pan when i drained it. after doing research, most people said it was the head gasket. I found that difficult to believe because of how fast the oil was spewing out of my coolant resivoir. further research told me it could be the oil cooler gasket... I took the oil cooler out (water and oil mixed were inside the oil cooler) but the adapter gasket was in perfect condition. No faults or anything. I decided to test my oil cooler by sealing one side off to a block of wood, and putting the water in where the coolant would usually go. I did this and water began to flow out of the oil cooler where the oil filter would be if it was connected. Is that suppose to happen? Is it possible for there to be a fault or internat crack inside the oil cooler allowing them to mix? are there aftermarket solutions or do i pay $400 for a brand new oil cooler?
I have a 98 gt that had the same problem, it was intermixing in the aluminum oil filter/cooler adapter. The casting was very porous.
 

wmburns

SN Certified Technician
Aug 14, 2009
5,818
501
194
Houston Texas
It can’t be either because we’re talking about oil in the coolant tank but no coolant in the oil. Anybody have anything else I can check?
I don't think you understand what we are trying to tell you. At the oil filter adapter on the side if the block there is a spot where the output of the oil pump and the lower radiator hose comes together. There is a gasket there that keeps the oil and coolant separate.

Think about it. Because this spot is before the oil filter this is where oil pressure is at it's maximum. So if the gasket as failed this would offer a "possible" point where the oil pressure would force the oil into the coolant but not the other way.

Does your car have an automatic trans?
^^^This is also a insightful possibility. At first glance how could one tell the difference between motor oil and transmission fluid? Is this motor burning oil? What about the transmission fluid level? This may be something straight forward as a rotted out radiator.
 
  • Like
Reactions: General karthief

Pepe 98v6

New Member
Mar 29, 2020
3
0
1
21
Virginia
I don't think you understand what we are trying to tell you. At the oil filter adapter on the side if the block there is a spot where the output of the oil pump and the lower radiator hose comes together. There is a gasket there that keeps the oil and coolant separate.

Think about it. Because this spot is before the oil filter this is where oil pressure is at it's maximum. So if the gasket as failed this would offer a "possible" point where the oil pressure would force the oil into the coolant but not the other way.


^^^This is also a insightful possibility. At first glance how could one tell the difference between motor oil and transmission fluid? Is this motor burning oil? What about the transmission fluid level? This may be something straight forward as a rotted out radiator.
When I said it couldn’t be either I meant the timing chain cover or intake manifold because they were stating coolant leaking down into the oil pan

I pulled the oil filter and the oil pump found an o ring(in good condition) but no *gasket*

I have a 98 base model mustang(v6 not a v8), so I don’t have an oil cooler in between the filter and the pump it looks like it just becomes the engine block after the oil pump it doesn’t look like coolant passes through/around the pump so I don’t understand why even if that o-ring was bad or if their was a gasket missing why it would be leaking into the coolant and not just straight out
 

o willingham

Member
May 14, 2020
26
3
13
Oregon
Pepe,

I had the same problem with my truck. I don’t know if it’s the same, but I had transmission fluid mixing with coolant. It looked like coffee. I found out the transmission fluid rans through the lower part of the radiator to help cool it. The radiator failed, which allowed the coolant, and transmission fluid to mix.
 
Thread starter Similar threads Forum Replies Date
J 1998 Ford Mustang GT First Mods 1996 - 2004 SN95 Mustang -General/Talk- 0
8 Electrical 1988 2.3L EFI to 1992 2.3L EFI engine 2.3L (N/A & Turbo) Tech 2
B 98 v6 engine swap with 95 v6? 1996 - 2004 SN95 Mustang -General/Talk- 1
T Where is the high pressure switch located on 1998 ford mustang base..? 1996 - 2004 SN95 Mustang -General/Talk- 10
C 98 GT A/C not working (Read more please) 1996 - 2004 SN95 Mustang -General/Talk- 2
Chythar SOLD 1994-1998 Ford Mustang GT Seats, Front and Rear, Black Fabric Interior Exterior Parts 4
S SOLD Jacksonville, Fl / 1998 Mustang Gt Convertible / 50k Miles / No Mods / Manual Trans / $7,500 SN95 Mustangs For Sale (1994-04) 2
G Expired 1998 Bright Atlantic Blue Ford Mustang Cobra Svt SN95 Mustangs For Sale (1994-04) 0
1998slowbra Drivetrain Clutch Release Fork Operation. 1994 - 1995 Specific Tech 1
B SOLD Lagrange, Ga - Ford Mustang Wheels (four) 1994-1998 (4th Gen) Stock Oem Used No Caps - $200 Obo Other Classifieds 0
T 1998 Ford Mustang Coup 3.8 The Welcome Wagon 3
5 Expired 1998 Ford Mustang Gt "low Miles" Vortech Supercharged Etc $7500 Obo SN95 Mustangs For Sale (1994-04) 2
Robbie Rich 1998 Ford Mustang Gt SN95 4.6L Mustang Tech 2
L Expired For Sale 1998 Ford Mustang Cobra SN95 Mustangs For Sale (1994-04) 0
tacomatrx450f SOLD 1994-1998 Ford Mustang Fiberglass Saleen Style Hood Interior Exterior Parts 0
M 1998 Ford Mustang Gt Track Hpde Road Race Street Car With Extras - $9000 Obo SN95 Mustangs For Sale (1994-04) 1
M 1998 Ford Mustang Gt Error Code P0500 SN95 4.6L Mustang Tech 1
MRaburn Brothers Performance 1998 – 2004 Ford Mustang Fuel Pump StangNet Site News 0
vitoGT F/S 1998 Mustang Ford Racing fuel pump 170 lph Engine and Power Adder Parts 0
9 1998 Ford Mustang SVT COBRA ( Supercharged ) 530WRHP 1 of 704 EVER IN CHROME YELLOW!! SN95 Mustangs For Sale (1994-04) 0
97_SALEEN_5.0 1994 - 1998 Ford Mustang Parts for Sale Interior Exterior Parts 0
K 2005 - 2006 Ford Mustang GT Engine & Transmission into 1998 Ford Mustang GT SN95 4.6L Mustang Tech 3
BTJustice 1998 Ford Mustang GT Engine Block Drain Plug Or Plugs SN95 4.6L Mustang Tech 1
S For Sale 1998 Ford SVT Cobra Black SN95 Mustangs For Sale (1994-04) 0
A Expired 1998 Gt Convertible. Might Be At Ford Nationals Carlisle Pa June 8th SN95 Mustangs For Sale (1994-04) 0
Corsec My 1998 V6 braking issues & what Ford is doing about it 1996 - 2004 SN95 Mustang -General/Talk- 5
K Sun visor replacement 1998 convertible 1996 - 2004 SN95 Mustang -General/Talk- 0
Mustang5L5 Install 1994--1998 Cobra Rear disk installation (M-2300-M instructions) Resource Discussion Forum 0
M 1994 - 1998 SN95 Mustang Paint/Color Guide - Production #'s too! 1996 - 2004 SN95 Mustang -General/Talk- 0
C Need a pdf of the 1998 Gt factory service manual SN95 4.6L Mustang Tech 0
C 1998 v6 automatic should I manual swap it? 1996 - 2004 SN95 Mustang -General/Talk- 4
G 1998 3.8L V6 overheating at idle, gauge doesn’t go up. SN95 V6 Mustang Tech 3
K 1998 v6 mustang grease for input shaft SN95 V6 Mustang Tech 0
JimmyJamTheHamSlam Part Suggestions 1996 / 1998 4.6L DOHC Mashup Engine Rebuild SVT Tech Forum 0
C 1998 Cobra engine bogs down when accelerating 1996 - 2004 SN95 Mustang -General/Talk- 0
C Steering Rack and Pinion differences between 1994 and 1998 1996 - 2004 SN95 Mustang -General/Talk- 0
rx79gez8gundam 1996-1998 4.6L SOHC Engine Harness Connector C210 Pinout SN95 4.6L Mustang Tech 2
W 1998 Mustang 3.8 auto transmission 1996 - 2004 SN95 Mustang -General/Talk- 0
M 1998 Coolant issues at manifold. SVT Tech Forum 1
W 1998 v6 3.8l mustang cranks but will not start 1996 - 2004 SN95 Mustang -General/Talk- 4
J What should I put in a 1998 GT roller? SN95 4.6L Mustang Tech 1
Neuron For Sale 1996-1998 Cobra Parts Other Classifieds 0
J 1998 GT i can feel the issue in the gas peddle 1996 - 2004 SN95 Mustang -General/Talk- 4
D 1998 mustsge gt heating problem 1996 - 2004 SN95 Mustang -General/Talk- 3
D 1998 Mustang gt The Welcome Wagon 0
GreenStangGT WTB/Trade 1994 - 1998 Cobra Front Bumper Cover Interior Exterior Parts 0
L 1998 Blower motor issues 1996 - 2004 SN95 Mustang -General/Talk- 2
M 1998 explorer 302 into 1989 car.... 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 3
J Help 1998 GT mustang The Welcome Wagon 1
B 1998 Mustang GT won’t stay running. SN95 4.6L Mustang Tech 3
Similar threads