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Replacing vs Rebuilding 5.3 in Alpha

cathairez

Member
Messages
9
Location
Evergreen, AL
I have a 2008 H3 Alpha. It has around 190k miles and is developing quite a bad oil leak. I tried the UV dye, only place the dye ever showed was the back oil pan bolt on passenger side. It wasn't as tight as the others, snugged it a bit and it seemed to help for a time. Then puddles started appearing again under the vehicle. I did a lot of googling, it suggested the oil sensor on top at the back of the intake (was dry no visible oil) and the valve cover with there being a recall on the pcv valve (clogs and supposedly causes leaks). I bought both the sensor and the revised valve cover as they were easy to put on, with the amount of oil it's started losing I really just did it because they were cheap easy parts and hoped I'd earned enough good karma (from decades of animal rescue), but I hadn't.

I tried looking around for replacement engines, so I could have one ready to swap one weekend (assuming I'm not sick/in hospital). I didn't want to pull mine, tear it down, have to find out what needed machining, boring, balancing, etc., then order the rebuild kit, then wait, then hope for good weather, etc. I cannot find a 5.3 LH8 engine anywhere. I've seen the DOD kits and from what I think I understand, you can take an engine from say a Silverado (please be gentle if I'm wrong), install the DOD kits, and be good to go?

Are there any other vehicles besides the Canyon and Colorado that had the same engine? What would be the best alternative 5.3 and which DOD kit would I need? Looks like there are a bunch of different kinds, brands, etc. Would it the computer need tuning or programming as I just want it to be stock, but a different engine would have different cam and such correct?

Sorry for all the questions, just trying to sort things out. I've only ever built one engine, an older 350 from the 80's and it wasn't bad. This seems to have a lot more potential for a screw up without proper planning.
 

cgalpha08

"Like Nothing Else"
Messages
3,581
Location
Indianapolis, IN
You shouldn't have any problem rebuilding the 5.3 you have. basically all of the guts are the same as any other gen IV gm LS engine. If you're tearing it all the way down with 200k miles on it, i would definitely take it to a machine shop and have it gone over before you reassemble it.

As far as other engines that fit, yea any old gen IV or LS3 type will fit, you'll probably have to move some of the engine accessories over and monkey with the air intake. The oil pan on the alpha is unique as well. I'm sure there are other parts that i can't remember. Then of course is the computer access, i do not think you can just hook up a similar gen iv and plug it in and have it run without some sort of tuning.
 

atvspeed4

Well-Known Member
Messages
1,171
Location
massachusetts
You just need to make sure that whatever Gen 4 engine you get has "car" style motor mount holes on the block. The alpha uses those not the standard truck motor mount holes on the driverside if I remember correctly. When our 2009 alpha cracked a piston it was cheaper for us to get a Gen IV 6.0L out of a 2500/3500 silverado. Just needed to do VVT delete, summit truck cam and swap over oil pan. We ran the gen IV intake manifold as the stock alpha one had cathedral ports despite being a gen IV motor. We made an adapter plate for the truck block to run the alpha motor mounts which worked perfectly. Was a super easy swap, cheaper and achieved 0.7L displacement increase at the same time. The stock tune did run the 6.0L for a little while while to get it to the tuner.
 

cathairez

Member
Messages
9
Location
Evergreen, AL
I will probably do the rebuild, but this will put my vehicle out of commission for a while. I have no garage to work in, so at mercy of weather, constantly sick with colitis to the point of needing blood transfusions, have broken ribs just lifting my own weight off the ground. Then I'm no professional, so it'll be going slow, double checking my double checking, looking up all the torque specs. Having only built one motor 11 years ago (that turned out fine), I just don't have the skill and speed to throw one together like a pro, though I know with caution and preparation it can be done.

If I have to get another 5.3L, is there a particular DOD delete kit that's more desirable than others, kind of a gold standard?

If for some reason when it's tore down, it's just not salvageable (not sure why it wouldn't be). The 6.0 swap sounds neat, but I'd be scared to try it without a guide to let me know if all the sensors and harnesses will plug right in (parts needed, etc), or if there'd be lots of splicing. Would the exhaust that's in the Alpha bolt right up or need modifying (could see that going either way)?

Thanks for all the replies and helping me get started/sorted. It was awesome not to be told to use the forum search or go google something.
 

Teahead

Well-Known Member
Messages
66
Location
Tacoma
oil leak still bad, but can't locate it?

If you have good compression and you're not burning oil, then I'd chase down that leak.

Maybe a rear main seal, but hard to say.

Be cheaper and easier to just fix the leak me thinks.
 

cathairez

Member
Messages
9
Location
Evergreen, AL
Yeah, the motor runs fine in my opinion. The only thing I could come up with is oil pan somewhere or rear main seal. There's no oil smoke, and when driving it's clearly burning outside the engine (can smell the oil on the exhaust and see it all underneath when you stop). It may fall apart today, but not running hot, power is still good.

I want to try an oil pan gasket, but watching the steps (on a silverado), you have to drop front diff which didn't seem bad. Then you have to drop the rack and pinion, or unbolt it rather, not take it loose from the wheels. There's one big bolt (i think a 21mm, that I can barely get a wrench on (going off memory here, kind of on top of the rack and pinion, but under radiator). I may ask the local shop how much it costs for the labor to put that gasket on. It'd be quicker and easier, I don't have air tools. I usually try and do all my work, but sometimes I just don't have it in me.

I have an inspection cam, took that and popped off the little round cover on the transmission. The flywheel and inside between transmission and engine were mostly dry, maybe 1/4 teaspoon of oil sitting in the very bottom. Someone told me if the rear main was leaking there'd be oil everywhere in there. Meanwhile the oil pan and exhaust, as well as things further back (blown from wind as I drive) are super oily. I've replaced both valve cover gaskets (as there was some oil accumulation on the passenger side cover, on the back corner near firewall. It wasn't a lot, and it appeared to be old, but I did it just in case.

I took the little camera scope and tried looking all around the intake between the firewall, but it's dry. Oil sensor was dry, front of engine is clean. Any other locations that I might not be thinking of?

I definitely agree on the cheaper thing. It'd take me a while to get all I need. Just googling the dod kits if I needed a new engine (don't think i would), $1000 ish, plus having a shop check the block and heads, plus tuning if needed. A gasket would be a lot cheaper and I'm treading water now , lol.
 

rascole

Well-Known Member
Messages
2,569
Location
Bellflower, CA
What dye did you use? I bought ACDelco 1148963 GM 10-5045 Leak Detection Dye from Amazon to troubleshoot a transfer case leak. I would use a small garden sprayer filled with degreaser and spray down the back of the engine and rinse several times to really clean it up. Wait until it is dark outside, add dye to engine oil and let it idle for a bit and use a UV flash light, leak will reveal itself in a bright fluorescent green.

https://www.amazon.com/gp/product/B008I2VPC4/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
1707524280320.png
 

cathairez

Member
Messages
9
Location
Evergreen, AL
I used that same dye pictured. It took about 5 minutes of idling. I had cleaned it with the gunk spray can product. Engine was spotless.

I saw a single drip, switched off the engine and started shining my light. It had formed on the back bolt of the oil pan, passenger side. I put my ratchet on it and turned it reasonably easy. I snugged it, but didn't have a torque wrench at the time.


No more dye was visible anywhere else.
 

cathairez

Member
Messages
9
Location
Evergreen, AL
Bought more dye, going to retest to tomorrow night. Broke a rib tonight just leaning over the chair arm. Too sore to try at the moment.

Shop said they would replace that gasket, 2 hours labor. So if I see more dye there I will probably let them do it. Gasket was about $50 on Amazon vs near $70 at local O'Reilly.
 

Nikal

Well-Known Member
Messages
85
Location
California
Not sure where your located? But where I’m at I have a great honest full service engine rebuild & machine shop. My 2009 Champion Edition 5.3 was leaking oil and I ran it down to them to find & fix. The two spots found was the oil pan was weeping, and right side valve cover gasket was leaking and causing my issue. They replaced both valve cover gaskets, oil pan gasket, while the pan was off they replaced the o-ring on the pick up tube as that’s a known GM issue, and can cause low oil pressure when the oil rings start to age and let it suck air. Also there is another common place they leak and that is the oil cooler block off plate above the oil filter. This can trick allot of people to think it’s leaking from the oil pan. This easily could be your issue as you are seeing oil on the rear pan bolt.

Here are a few pictures I found online to show you where it’s located and how it could be mistaken for an oil pan leak.

IMG_2613.jpeg

IMG_2612.jpeg


It’s very common for the 4.8, 5.3, 6.0 V8’s to leak at the remote oil cooler block off plate. My Silverado did this and I was thinking oil pan or rear main seal as to where the oil was seen. Literally a $10 gasket.

IMO spend a few bucks and let a shop diagnose it. If a good shop, they should figure out the leak pretty easily and get you fixed, for 10x cheaper then an engine rebuilt or replacement.
 

Jeeper360

Active Member
Messages
29
Location
NJ
I have thinking of this also crate ls3 6.2 for Camaro the trucks will not fir the oilpan or rebuild i think the hummer v8 5.3 is a aluminon lc9 so the ls3 will be heaver i am still reserching for a fall swap and trans is a new problem l60 to 65 ?
 

Teahead

Well-Known Member
Messages
66
Location
Tacoma
I have thinking of this also crate ls3 6.2 for Camaro the trucks will not fir the oilpan or rebuild i think the hummer v8 5.3 is a aluminon lc9 so the ls3 will be heaver i am still reserching for a fall swap and trans is a new problem l60 to 65 ?

you probably want to start your own thread.
 

cathairez

Member
Messages
9
Location
Evergreen, AL
Used dye after cleaning engine, it's coming from under the head of the rear oil pan bolts on passenger side. Close to 2qt a week depending on how much I drive.

Friend suggested thread sealer since bolt is super tight already apparently. Will try that soon.
 

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cathairez

Member
Messages
9
Location
Evergreen, AL
In case I do have to do this myself, what size bolt/nut is the one that runs vertically up through the cross member, the nut is kind of almost under the radiator (just going from memory), on the rack and pinion. I know the horizontal are supposed to be 18 and 24 mm, just the vertical I'm not sure of.

Wanted to pickup that size if I don't have.
 

Teahead

Well-Known Member
Messages
66
Location
Tacoma
Sounds to me the oil pan gasket needs changing.

I'd try replacing that first before changing the engine.
 

cathairez

Member
Messages
9
Location
Evergreen, AL
I am trying to fix it, since the leak seems to be found. I put thread seal on tonight, but its one of the long bolts with hardly any threads.

I'm hoping to do it all myself, broke rib is killing me though.

I just am curious now what size bolts hold the rack and pinion on. Tried watching a video on a silverado, seemed to be 24mm and 18mm, but none of their bolts run vertical, the H3 has one on the driver's side. Most all my sockets are the 14mm or smaller, wrenches 19mm or smaller, just want to get all the tools on hand in case the fix doesn't work with the thread seal in the pan bolt.
 
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