Mystery Leaking in Engine Bay on Passenger Side

[beepbeepyellowjeep]

Howdy folks. I've had my '03 4.0 for going on fifteen years but this is the first time I'm feeling in over my head. I have a mechanic I can take it to, but he's semi-retired so I try to avoid unless I absolutely cannot figure it out. If this is dumb-simple feel free to tell me so; I'm not a wrencher by nature and I'm not that much older than the jeep so I don't have a lot of experience.

Back in September I had a coolant blowout on a hot day; engine overheated in a less than a minute and broke out the heater core inlet. Ended up bypassing heater core and replacing radiator due to visible bubbling on it. Had coolant leaking under the body and so we replaced the water pump too...and then noticed coolant (apparently) spraying down the passenger side of the engine/coil rail/oil filter so we replaced the thermostat and housing too on Thursday(12/4). Which, to be fair, we should have replaced all of that at the same time way back in September, but I didn't have this forum then so live and learn.

Drove it Friday (12/5) and it was bit hot, just a touch past the 210 midline, but I figured it probably needed to burp some air. Didn't drive it Saturday, went out today(12/7) to check the coolant level and saw that it looked like there was still spray in the same places, wet still even. See pictures for what I'm talking about. The only thing I can think of is a head gasket, but we changed the oil a month and a half ago(200ish miles) and it was fine so coolant isn't going into the oil. I can't really tell if it's oil or coolant, because the engine is generally greasy so touching it to feel didn't really work but the oil was so recently changed so it would be very thin and light like I'm seeing.

Unrelated (I think) is that I had rough running back in October, so we replaced spark plugs, then I got P0301 and P0303 codes recently so we did the injector 3 hot soak fix and replaced the ignition coils and rail for good measure. Seems to have not had any issues since with the engine itself, beyond running a bit hot.

What am I missing? Should I scrub down the engine/bay real good and see what happens after I drive it a few days? This is my daily driver, but it gets very little mileage (5-6k/yr) because I have a motorcycle I ride quite often when the weather is good. I appreciate any advice y'all can offer! I want to keep this jeep long enough to teach my kids to drive stick on it, so I'm willing to invest in what it needs to keep it around that long.

 

[macleanflood]

Pressure test the coolant system.

You can "rent" a tester from most auto parts stores.

My guess is head gasket...but a pressure test...followed by possibly a combustion gas test, compression and leak down tests will confirm the diagnosis.

Head gasket isn't a tough job. Hardest part is getting the exhaust header off the head. Newer the Jeep the more cats. Did my neighbors 04 WJ's head gasket in my gravel driveway.

-Mac

 

[Chris]

X2 to the above. Mac nailed it.

 

[beepbeepyellowjeep]

I know a guy who works on diesels and I bet he has the gear to run some of those tests, I'll hit him up. I hate to take my jeep by cause he's always asking when I'm gonna throw a cummins in it, but he can probably help with this.

Stupid question alert, but what is "cats" in this context? I've only ever heard it referred to catalytic converter but that's down before the muffler?

 

[lBasket]

 

[beepbeepyellowjeep]

I mean, I have one of those too, but he generally stays out of the jeep and sticks to the boxes parts come in instead.

 

[macleanflood]

I've only ever heard it referred to catalytic converter but that's down before the muffler?

Yes. They're stuffed in there with often rusted and siezed bolts. If you have a can of your favorite penetrating lubricant start hosing them off now.

-Mac

 

[beepbeepyellowjeep]

Yes. They're stuffed in there with often rusted and siezed bolts. If you have a can of your favorite penetrating lubricant start hosing them off now.

-Mac

Wilco

 

[beepbeepyellowjeep]

Pressure tested the coolant system to hell and back with nothing to come from. Gonna wipe it all down good and see what happens over the next couple weeks driving daily while keeping an eye on all the fluids. In the meantime I'm gonna look into that combustion gas test and the rest; I want to be as sure as I can that's the issue and I start pulling things apart.

 

[JKP]

A lot of that coolant was above the head gasket.

The fan, pulleys, and belt will sling it everywhere.

I had coolant on the passenger fender and AC compressor on my YJ from the water pump....

 

[beepbeepyellowjeep]

A lot of that coolant was above the head gasket.

The fan, pulleys, and belt will sling it everywhere.

I had coolant on the passenger fender and AC compressor on my YJ from the water pump....

That was my thoughts, too. A pinprick, under high pressure, at the front of the engine, could spray it like this and send it that far back. Obviously not pictured, but the fuse box, battery, all that has splatters too.

But with everything new and seemingly working well and passing the pressure test...I don't know. Maybe there was residual somewhere that didn't dry up due to low outside temps keeping the engine from warming up enough to dry it off?

It's clean now so we shall see what happens in the next little while.

 

[Moglocker]

That was my thoughts, too. A pinprick, under high pressure, at the front of the engine, could spray it like this and send it that far back. Obviously not pictured, but the fuse box, battery, all that has splatters too.

But with everything new and seemingly working well and passing the pressure test...I don't know. Maybe there was residual somewhere that didn't dry up due to low outside temps keeping the engine from warming up enough to dry it off?

It's clean now so we shall see what happens in the next little while.

Looks like that hose clamp in the pic,all clean now it should be easy to spot

 

[Chris]

That was my thoughts, too. A pinprick, under high pressure, at the front of the engine, could spray it like this and send it that far back. Obviously not pictured, but the fuse box, battery, all that has splatters too.

But with everything new and seemingly working well and passing the pressure test...I don't know. Maybe there was residual somewhere that didn't dry up due to low outside temps keeping the engine from warming up enough to dry it off?

It's clean now so we shall see what happens in the next little while.

UV dye can also help in situations like this as well!

 

[GoldenGorilla]

Lots of good info in here.

Regarding the engine being greasy, the CCV grommets on the valve cover tend to shrink and leak as they age. New CCV valves and grommets will put an end to that. The front and back elbows are different.

 

[beepbeepyellowjeep]

Lots of good info in here.

Regarding the engine being greasy, the CCV grommets on the valve cover tend to shrink and leak as they age. New CCV valves and grommets will put an end to that. The front and back elbows are different.

Oh that is good to know, there is absolutely some gunk on the front one.

Latest is that I was still getting splatters everywhere, and in a fit of midnight insomnia I decided to get (another) new radiator cap, because that was the only thing I could think of in the coolant system that didn't get put under pressure in the pressure test. So far no more splattering, but time will tell. Still no other symptoms of a head gasket issue, but again, we shall see.