Oil leak under coolant temp sensor (1 Viewer)

[etx]

Hey guys. Stats up first. 1996 fzj80. 195,000 miles. I've searched and haven't found anything about my problem so here goes. I have a slow oil leak. It appears to be where the head meets the block, right under the engine coolant temp. sensor. This sensor is above the oil filter and just to the left. I imagine the only culprit is the head gasket. I looked at pictures of the gasket and can't tell if there are any oil passages close. No oil in coolant or vice versa. Was running rough, changed cap, rotor, wires, and plugs and runs fine now, but thats when i saw the oil on the block. Does anyone have experience with this. Seems like the majority of gasket fails are at cylinder 6. No overheating or anything of that nature. Thanks In advance!

 

[BILT4ME]

Valve cover gasket
Distributor O-Ring seal
Spark Plug tube seals

Those are the most common culprits. Do all three at the same time.

 

[jpoole]

Pictures?

Could it be the timing chain cover?

I assume that blowing from the fan may be causing oil to run towards the rear of the block, as well as down so keep an eye forward and above for this leak.

 

[etx]

I'll get some pics tomorrow in the daylight. There's no oil on the side of the head itself so that makes me want to rule out valve cover gasket and plug tube seals. The dist. O-ring is good, the spot is pretty localized, but I will check again tomorrow just to make sure. Will inspect timing cover as well. I cleaned the area and drove it to isolate the leak and it appears to be as I xescribed, but I will verify. Thanks for the input, don't wanna change the head gasket haha!

 

[etx]

It's hard to get my phone at a low enough angle, but the seepage is coming from right under the coolant temp. sensor. I've been looking at head gasket pictures and wondering which holes oil goes through, maybe one is close to this location? Anyone know?

 

[etx]

Action shot. Old girl at work.

 

[jpoole]

What does it look like above the intake runner? Is it possible that the VCG is weeping and that it's hard to see the oil until it puddles on the top of the block?

I'd clean that area with a degreaser all the way up to the VCG really well and then keep an eye on it. If the oil returns and the surroundings are spotless you will be better able to pinpoint it's source. There are enough trailings on the head in that picture to lead me to believe that the oil is coming down from above but it's hard to be certain from one pic.

 

[etx]

Thanks jpoole, I will do that for sure. It's hard too see for sure with the dang plenum in the way. I really appreciate the advice and will report back with findings.

 

[Tools R Us]

Agree, running to there, gravity makes it run down, the fan blows it towards the back. My bet, valve cover gasket, possible cameo appearance from the distributor o-ring.

 

[sailingcruiser]

I had the same problem on my 97 right after I bought it. It ended up being the rubber o ring on the oil filter squirting oil up near the sensor. When I changed the oil I realized that the rubber was hard. and the oil filter was not quite hand tight. It took me days of head scratching to figure out.

 

[Proven]

I like to think of these oil leaks as "corrosion control".

I was going to say that this just looks like where the puddle stopped since there are oil signs all around that sensor.

 

[roncruiser]

It's hard to get my phone at a low enough angle, but the seepage is coming from right under the coolant temp. sensor. I've been looking at head gasket pictures and wondering which holes oil goes through, maybe one is close to this location? Anyone know?View attachment 1713088

What did this end up being? I have the same exact thing happening on my vehicle and posted a thread the same as your thread here. I documented with photos on my thread. Shows the same. Got the same responses which did not end with a resolution.

Any luck?

Was not from a leaky or bad valve cover gasket or leaky or bad distributor o-ring. Mine also shows dripping oil from the coolant sensor connector. From which I cannot source where its coming from. Weird.

Reference: My thread on the same...
Help identify these sensor...