View Full Version : st165 oil leak. need help bad

08-28-2011, 03:35 PM
Hello all, i have an st165 (gen 1 3sgte) and i for the life of me can't find an oil leak. it's quite a substantial leak, a good size puddle is in my garage after a drive. it is coming from the back of the engine, nearest the firewall, and it is NOT i repeat NOT the valve cover gasket, as i just changed it today and there is no more clean oil on the injectors or anywhere around the gasket. i used blue loctite and black rtv in the correct places so it's not that.

could someone with st165 specific experience tell me where this might be coming from. i have seen lots of pictures of the back of st185/205 motors, but these pictures don't really help because there are a lot of differences between the gen 1 and gen 2/3/4 3sgte's.

even better, could someone post a picture of a gen1 3sgte intake side(back) while the engine is out. just a good overall picture of the entire back side of the motor so i can maybe find out what could possibly be leaking.

someone please chime in, i miss driving without having to worry about running out of oil (yea, it's that bad). thanks in advance

08-28-2011, 05:31 PM
There are some differences between all the engines but all the big stuff is the same.

There are plenty of places to look so sometimes leaks are a bit tricky to pinpoint.

My shortlist of things off the top of my head:

-oil pan seal
-oil pump
-front main seal
-rear main seal
-head gasket

08-28-2011, 05:43 PM
I don't think its the oil pan seal as the leak originates higher but I will check. Most of the dripping is coming off the lower part of the sump and some off the exhaust. Mostly on the passenger side of the motor so I don't think is the distributor either. I will try and get it onto a lift to get some pictures for you guys.

08-28-2011, 09:20 PM
Probably not this due to the location - but I once had a bad leak that I just could not find on an old Corolla. This leak would make for a substantial puddle under the car but I just couldn't find it. I needed to add about two or three quarts of oil after my drive of ~75 mi. home everyday. I would start the thing up and look underneath and see no signs of any leak that would cause that much loss of oil.

I figured out that the leak would only happen after a drive when the thing was hot, so when I came home from an extended interstate drive I got under the thing right after I switched it off and found the problem was the oil pressure light switch. The epoxy "potting" had a pinhole leak that would only leak when the thing was really hot after it was turned off - I could see a geyser of oil squirting out.

08-28-2011, 10:35 PM
Well I don't think I have an oil pressure light. Just the pressure sending unit on the front drivers side of the head. Its about that bad though. The oil isn't even dirty when it comes out. I'm putting about a quart every three trips back and forth to work 30 miles. So I guess I should be looking for geysers.

Also mine does only leak after I drive it. In the driveway no leaks at all. Only after driving. So something that has to be under load. It won't leak even when at operating temp in the driveway. Only after driving. Maybe this will help narrow things down

08-29-2011, 12:52 AM
Yea - well switch - sending unit - they are the same thing - only one is a switch that controls an "idiot light" and the other a transducer that outputs an analog voltage to a gauge.

It could be anything that accesses the internal oil system.

Anyway - just food for thought - when you start it up it is cold - when it is running it is at operating temp being cooled by the water circulating in the block - but after you drive it for awhile and then shut it down it briefly heats up allot more without the water circulating before it cools down slowly. At that time the temp is really hot and there is still allot of pressure there too. Couldn't hurt to do as I did - switch it off hot and look underneath as quick as you can. A leak like that should be noticeable.

08-29-2011, 01:21 AM
i will do that tomorrow night after i get back from my school orientation. thank you for your help.

08-29-2011, 02:02 AM
This might be a long shot as well but because you said it was coming from your passenger side, check the crank pulley seal. It will leak when in motion and warm at decent RPM, but as soon as you turn the car off it will stop because it is no longer in motion. Just throwing that out there.

08-29-2011, 02:16 AM
Well I would assume that that is under the lower timing cover, which is not leaking or dripping. No oil anywhere on the timing cover. I will check the seam when I get home but I don't think it is.

08-29-2011, 04:49 AM
Trying to diagnose something like an oil leak over the internet is quite hard..

My advice would be to clean it (degreaser and pressure washer), drive around the block and then take a good look. Should be obvious at that point.

08-29-2011, 02:07 PM
Well its kind of hard to tell after I do that, I think as it drops off the motor it huts the axle and its slung all over

08-29-2011, 04:57 PM
headgasket or cracked head is my guess

08-29-2011, 05:19 PM
headgasket or cracked head is my guess

That would be my guess.

I would roll it on ramps and wipe down/clean everything. Take it for a spin then place cardboard underneath, or yourself, to see if it gives a more exact spot.

08-29-2011, 07:28 PM
Don't st165s usually crack in the front of the head where the alternator hangs off? I mean if that's the weakest part that would crack first wouldn't it be there first. And its not cracked there. Head gasket maybe. Compression test was 145s across the board so could it be a head gasket still? Are there any pursue sensors on the intake side of the motor?

Could it be that the previous owner had used conventional oil for the first 85k miles and now that I have started to use synthetic something may have opened up?

08-29-2011, 07:37 PM
Synthetic can cause a leak if the gaskets were old or there was alot of build up hiding weak gaskets. I have heard that happen, just never first hand.

08-29-2011, 10:51 PM
If the spinning axles sling the oil dripping on them, try cleaning it, then running the engine in neutral at a decent RPM. No spinning axles, but sufficient heat and pressure should build up.

Passenger side leads me to think oil pump -- your description sounds much like my bad oil pump seal -- but there's too many possibilities to be certain without actually looking at it.

08-29-2011, 11:03 PM
I guess I should have been more specific. by the time the oil has reached the bottom of the engine where it drips on the ground, the only part that isn't dripping is the tranny. Everything else either has a light coating or is dripping. Most of the droplets just happen to be on the lowest part of the oil pan and the exhaust. I'm going to try and take a picture for you guys when I get home, in about 3 hours.

10-15-2011, 12:19 AM
My guess would be crank shaft seal if its on your passenger side. You wont see anything around your timng cover since the crank is kind of low. If youd see oil on your timing cover it'd be the cam seals...good luck but pictures would definitely help a lot!