Stumped on oil leak

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

RanchWelder

Full Access Member
Joined
Jan 14, 2023
Posts
798
Reaction score
1,144
Location
Earth
First Name
--------
Truck Year
87
Truck Model
Blazer
Engine Size
355ci
Yup the hammer. Lil' patience, not too much torque, some gasket on the brush for every bolt thread and just enough gasket sealer on each side of the paper to make it sweet, not squish.

The secret some transmission guys use, is to make certain there is a good round gob of gasket sealer directly under the head of every bolt. Just enough so they can verify it has seeped out around the bolt when tight. That's how they KNOW their work has been opened and the reason it leaked after being screwed with by somebody else. This fills in the circle of metal in a pan gasket and stops the bolts from weeping.

The gasket sealer rusty mentioned says to spread it thin (on both sides of the paper or rubber), hand tighten and let sit for an HOUR, then torque to spec.

If your rubber gasket is wet, spend a few bucks on a 1 quart can of Acetone.
Wash everything sparingly wearing the gloves and clean every steel surface nice.
Your wife/girlfriend will love you for buying her the rest of the quart for her nails!

It don't have to be perfect, just good.

#2 for not going cork.

You got this.
 

jamesscruffy

Junior Member
Joined
Jul 12, 2024
Posts
2
Reaction score
0
Location
Texas
First Name
James
Truck Year
1985
Truck Model
C10
Engine Size
350
Groove on harmonic balancer, were it meets timing cover seal, then you need a speedy sleeve
 

RanchWelder

Full Access Member
Joined
Jan 14, 2023
Posts
798
Reaction score
1,144
Location
Earth
First Name
--------
Truck Year
87
Truck Model
Blazer
Engine Size
355ci
Yah, the sleeve could be worn too.
I like the blue gel anaerobic thread locker on the cover as a seal.
If it's worn out wrong or the main seal is effected, buying a quality or sourcing an OEM cover might be required. Sometimes they punch the main seal off center for the bolts.

This could be why your threads ate the hole on the bolt you show.
My bad for not realizing it could be a poor stamped aftermarket modern cover.

Many sales threads from aftermarket main seal manufacturer's have complaints from faulty manufacturing issues causing leaks in the timing cover sets.
It's worse in the timing gears responses.

Seems you could buy three in a row from different companies and get a leak.

You probably need a new cover from an OEM engine to get it right, at this point, with so much crap aftermarket stuff in the system.
 
Last edited:

ChuckN

Full Access Member
Joined
Nov 8, 2022
Posts
1,302
Reaction score
3,950
Location
Bellinham, WA
First Name
Chad
Truck Year
1981
Truck Model
C10
Engine Size
350
You must be registered for see images attach


If you end up doing the pan gasket, get one of these. They are the bees-knees. They’re reusable, very forgiving, and even come with thread in “snap-ups” that hold it in place for you while you thread in the pan bolts. Just put a little dab of Ultra black or Ultra gray in the corners where the circles of the timing cover/rear main meet the flat part of the block surface. You’ll have it for the lifetime of the truck.
 

Bronze Knight

Full Access Member
Joined
Aug 4, 2020
Posts
75
Reaction score
180
Location
USA VA
First Name
Robert
Truck Year
1985
Truck Model
K30
Engine Size
454
I was joking about the cork gasket guys lol. I have a one-piece oil pan gasket on there now. However, I have another one coming because the RTV is in the gasket now and even if I dig it all out I'm not willing to do this AGAIN so I'll use a fresh gasket. I don't think i need the Sleave on the crank that seal does not look like it was leaking. for the UV dye I think it was more the edges of the timing cover gasket and the bottom of the oil pan gasket.

The timeing cover I'm not so sure I can pound it back into shape. the places where it is bent are the spots the locating tabs go through, not bolts. Furthermore, it looks like the metal has been stretched I know it doesn't show up in the pictures very well but it is. Like the cover was pushed upwards and bent. So even if I got them flat I think there will still be a gap at the bottom of that hole.

Anyway, now I have to wait for the parts. I was going to get it all from Rock Auto but the shipping made it $20 more than amazon.

You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
 

JBswth

Full Access Member
Joined
Jan 24, 2022
Posts
225
Reaction score
182
Location
Vallejo, California
First Name
James
Truck Year
1973
Truck Model
C25
Engine Size
292 cubic inches
Yep PCV vent was the issue. I swapped out the Valve covers when I put the engine back in and I did not realize that the old ones had a breather-style oil cap. So when I put the new ones on I plugged up the driver's side valve cover. I talked to my brother who used to be a mechanic about it over the weekend and he gave me a few things to test. One of those was to get the engine hot and then clamp off the line between the PCV valve and the carberator. I did that and at idle it would start puking oil out of the dipstick tube about 15 seconds later.

You must be registered for see images attach


(It’s green because I used a whole bottle of UV dye)

So then I read up on the PCV system in the "Fuel, Driveability and Emissions Service Manual" and realized my mistake. Picked up a breather filter at the auto parts store put it in and clamped off the line between PCV vent and the carberator, again at idle, and this time I did not get oil coming out of the dipstick. So I took it for a test drive around the neighborhood again and I did NOT have a cloud of oil smoke coming off of my headers.

You must be registered for see images attach
You must be registered for see images attach



Still have a leak around the timeing chain cover. I’ll redo that with as much RTV as I feel I can and see if that fixes it. I may have to pressure wash the engine first to try and make sure it’s coming from the timeing cover.
Good that you found the cause of the oil getting on the headers, but putting RTV on the timing gear cover will be a temporary fix at best, as oil in back of it will eventually push it off. If cap screws on the cover are all properly tightened, then you need to remove it and clean the mating surfaces and replace the gasket. That's the only way to permanently fix the leak.

J. B.
 

Bronze Knight

Full Access Member
Joined
Aug 4, 2020
Posts
75
Reaction score
180
Location
USA VA
First Name
Robert
Truck Year
1985
Truck Model
K30
Engine Size
454
It’s raining here which is not ideal. And I pulled a muscle in my back last weekend still getting over that. But I wanted to get something done today so I drained the oil and removed the pan. Looks like the plastic sleeve on the oil pump shaft is AWOL pump itself looks fine but I’m going to put the new one in. From what I can see of the cylinder boars they look OK.
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
 

Bronze Knight

Full Access Member
Joined
Aug 4, 2020
Posts
75
Reaction score
180
Location
USA VA
First Name
Robert
Truck Year
1985
Truck Model
K30
Engine Size
454
Wow lookie there!
Ol boy dropped pan with the filter installed.
How bout that.

Yep It wasn't in the way. I got the oil pump done and put the pan and timing cover back on. Hopefully tomorrow I'll get it all back together.
 

Bronze Knight

Full Access Member
Joined
Aug 4, 2020
Posts
75
Reaction score
180
Location
USA VA
First Name
Robert
Truck Year
1985
Truck Model
K30
Engine Size
454
I just wanted to thank everyone here. I got everything back together last week and test drove it and I think this problem is done at last. I’ve taken it around the neberhood a few times and took the wife out to get ice cream yesterday. No leaks. There is more to do to the truck but at least I can drive it and use it for truck things now.
 

Bronze Knight

Full Access Member
Joined
Aug 4, 2020
Posts
75
Reaction score
180
Location
USA VA
First Name
Robert
Truck Year
1985
Truck Model
K30
Engine Size
454
....

Spoke too soon. I was feeling good about the truck so I drove it to work on a Friday a week or two ago. Everything was good on the way into work. But on the way home at every stoplight I was getting a small oil smoke cloud. Made it home thankfully but when I looked in the hood the oil dipstick was out of the tube a little bit and I had oil on the inner fender and all down the underside of the passenger side of the truck. This was somewhat disappointing but life goes on. Anyway, I got back to it last night and ran a compression test and it looks like cylinder 3 has found something better to do.

So now what? I have a few options that I can think of. The first is to redo the rings and main bearings. I have never had an engine that far apart before and I am willing to try. But I wonder is that my best option? It could be a bent or stuck valve, and then I'd have to look into redoing or replacing the heads and all those parts.

No matter what I think I'll have to pull the head(s) off and look at them but again I've never torn an engine apart that far and I'm worried I'll miss something.

You must be registered for see images attach
 

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
5,433
Reaction score
8,648
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
Mark #3 position on the distributor body pull the cap,disconnect power to the HEI and rotate the motor until the rotor is pointing at your #3 mark. Screw an air fittings into #3 plug hole take of the oil cap and put a rag over the hole,then hit it with some air. If air hisses out of the carbureator you have an intake valve problem if it hisses out the exhaust you have an exhaust valve problem if it blows the rag off the valve cover, you have a bad oil cap. JK if it blows the rag off you're probably looking at rings,maybe a piston. The thing about the bad oil cap I was doing this exact thing at work,rag in the tail pipe,rag over the throttle body,rag over the oil fill. Service writer comes over and asks what I'm doing. And the way I explained it to you,with the bad oil cap,that's how Dave explained it to the service writer. Lol,and he believed it
 
Last edited:

Latest posts

Forum statistics

Threads
44,136
Posts
950,090
Members
36,241
Latest member
Blacklabelcustoms
Top