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H3 Comments on oil leaks 5.3L

K0PIR

Well-Known Member
Messages
216
Location
Pierre, SD
I am in Englewood, Co. and looking at 2008 H3 Alpha. It looks very clean other than underneath. Looks like the oil pan gasket is leaking, maybe the rear seal and that large gasket on the rear. I also noticed some fluid leaking on the front passenger disc. Maybe brake fluid I’ll have a closer look at it.

It’s got 210,000 mi but looks good. Has rear lockers. It’s in a enclosed warehouse and I haven’t driven it yet, but the center diff locks and the rear locker works. At least I hear them working.

Comments??? Does it look about normal for a 5.3L with 210,000 mi.?

TIA,
Rich
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Last edited:

Gpcalero

Well-Known Member
Messages
234
Location
SW Florida
I am in Englewood, Co. and looking at 2008 H3 Alpha. It looks very clean other than underneath. Looks like the oil pan gasket is leaking, maybe the rear seal and that large gasket on the rear. I also noticed some fluid leaking on the front passenger disc. Maybe brake fluid I’ll have a closer look at it.

It’s got 210,000 mi but looks good. Has rear lockers. It’s in a enclosed warehouse and I haven’t driven it yet, but the center diff locks and the rear locker works. At least I hear them working.

Comments??? Does it look about normal for a 5.3L with 210,000 mi.?

TIA,
Rich
8c56700287576c414caa832726b79808.jpg



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210k is a bit of miles even though 5.3's are troopers. Never know how long it's gonna last when it gets to that point lol.

Not really a way to tell if that's normal. Some trucks may get up there in miles and never leak. Assuming it's fine, you still have a bit of work to do to fix the leaks though. The oil pan gasket is annoying to do but is the least of your worries if you are thinking of replacing the rear main seal.

I'd see if whoever is selling it would take care of replacing the gaskets so you don't have to. Probably won't but it's worth a shot
 

K0PIR

Well-Known Member
Messages
216
Location
Pierre, SD
Thanks for the input. I am going to test drive it and see what happens.

Rich


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JPaul

Well-Known Member
Messages
2,400
Location
Way up north, UT
At 200k+ I'm not surprised it is leaking. How much and from where would require cleaning the whole thing and then seeing where it is really coming from. If it's just the gaskets then it wouldn't be too bad a job to just replace them. Drop the front diff support to get the oil pan off. If the rear main and/rear block plate are leaking then you have to unbolt the transmission, push it back, and replace the gaskets. The transmission bolts are a pita to get to the top few. Small hands help as does a helper. Front block plate is only a pain due to how much stuff has to come out and off to replace it, but otherwise a reasonable job.

Frankly, what you do with it is up to you and what you want the rig for. If the price is right and you want to make it all nice and have the ability then I would plan on just pulling the engine and giving it a good tear down and refresh with new bearings, seals, rings, etc.

Otherwise if you don't care about all that or can't afford it then just see how much it is really leaking and go from there. It might not be much of a leak and just has spread around over time. Hard to say from one picture.

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K0PIR

Well-Known Member
Messages
216
Location
Pierre, SD
At 200k+ I'm not surprised it is leaking. How much and from where would require cleaning the whole thing and then seeing where it is really coming from. If it's just the gaskets then it wouldn't be too bad a job to just replace them. Drop the front diff support to get the oil pan off. If the rear main and/rear block plate are leaking then you have to unbolt the transmission, push it back, and replace the gaskets. The transmission bolts are a pita to get to the top few. Small hands help as does a helper. Front block plate is only a pain due to how much stuff has to come out and off to replace it, but otherwise a reasonable job.

Frankly, what you do with it is up to you and what you want the rig for. If the price is right and you want to make it all nice and have the ability then I would plan on just pulling the engine and giving it a good tear down and refresh with new bearings, seals, rings, etc.

Otherwise if you don't care about all that or can't afford it then just see how much it is really leaking and go from there. It might not be much of a leak and just has spread around over time. Hard to say from one picture.

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Thanks. I got a chance to drive it and the shift fork must be broken in the transfer case. It wouldn’t go back into 4hi unless I backed up. So there’s that too.

Sure is a nice Alpha with rear locker, just needs some engine work.

I drove two of them while in Colorado and I don’t think either one of them drive as nice as the one I have now (06). I just want the V8 for towing my camper.


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alrock

El Diablo
Staff member
Messages
10,442
Location
Scottsdale
From what I recall Reloader saying, oil pan leaks and rear main seal leaks are common on the 5.3s, and not exclusively to H3s. He's replaced both on his Alpha.
 

Reloader

Well-Known Member
Oil pan gasket leaks very common on these engines. 4.8, 5.3, 6.0 and 6.2 all use the same gasket. Use Felpro or GM gasket and always, always, always replace the oil pump pickup tube o ring where the tube goes into the pump housing in front cover. The pan gasket inner rubber bead looses its ability to seal with time and you can't tighten bolts anymore because gasket is aluminum. There are two pressure passages from block to oil filter and back to block. This is where it leaks primarily. There is a small block off plate above the oil filter that can leak also. Its where oil cooler lines attach if equipped. Replace also. I do these in an H3 in 6 hours. I remove front diff and crossmember. Makes it lots easier. You remove starter to get plastic filler piece out of the way. Just unbolt starter and slide foward if needed. Its very critical to properly tighten pan and trans bolts correctly. Start all pan bolts and snug slightly. Snug up 2 lower bell housing bolts. Loosen pan bolts a bit then tighten 2 bell housing bolts to say 15 ftlbs. Start tightening pan bolts on front half of pan . Loosen bell housing bolts then tight rest of pan bolts to spec. Pan should be tight against the bell housing so you can tighten the 2 bolts to specs.
Dont forget to proper clean both mating surfaces. I use brake cleanr and 3M pads. Only use RTV on the block side at the points where front cover and rear seal holder join the block. A small dab will do. If truck has more than say 130K on it, consider replacing motor mounts too. Much easier while diff and crossmember is removed. I do pull front CV axles to remove diff and I install new seals . They are cheap.
Rear main seals on these ingines are a non garter spring elastomeric type seal. Not prone to leaking in my experience. Get seal from GM. Comes complete with mounting plate, gasket and bolts. I replace it when ever I remove transmission usually.
Any questions, just ask.
That is all.
 
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