Hi team, got a 94 gmc c1500 Sierra Sle 5.7 v8. I got about 362k on it, rebuilt transmission, and I’ve kept up on regular maintenance. Recently my trucks been overheating, it’ll come out thru the radiator cap (which I’ve replaced three times) but it doesn’t have any obvious leakage. I know it’s my head gasket or whatever it is but I wanted to see if u guys think it’d be a good idea to rebuild the engine with a rebuild kit, or just get a new engine.
Rebuild or Replace?
- Thread starter i3vil
- Start date
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Drunkcanuk
I'm Awesome
Not giving you an answer.......yet. only more questions for you.
Is that the extent of your diagnosis, that it's coming through the cap?
Is the oil all discolored like a milkshake?
Is it smoking white out the exhaust and smelling "sweet"?
Did you pressure test it?
Is it a daily driver or can it be down for a while?
What's your mechanical ability?
Budget for rebuild or
replacement?
Is that the extent of your diagnosis, that it's coming through the cap?
Is the oil all discolored like a milkshake?
Is it smoking white out the exhaust and smelling "sweet"?
Did you pressure test it?
Is it a daily driver or can it be down for a while?
What's your mechanical ability?
Budget for rebuild or
replacement?
OK, it's tired.
How do you know it's overheating? What is the temp gauge showing? What temp does the computer think the engine is at when you connect a scan tool and look at the temp sensor data?
If this is a head gasket that leaks and pressurizes the cooling system, it may not be overheating at all.
Depends on your skill level, experience, the tools you have or have available, the availability of a decent machine shop local to you, and whether you have a secure and CLEAN place to do the removal, teardown, inspection, cleaning, assembly, and reinstallation. Are you prepared for all that?
Buying a "new" or "rebuilt" engine will be easier and probably quicker; but also more expensive. You're trusting someone else to do a big job correctly.
In addition to the actual engine, you're probably going to need a fresh radiator, fan clutch, fluids and filters, exhaust work, and various accessories--water pump, distributor, belts 'n' hoses, and more depending on what you find as you disassemble.
I think you need a little more diagnosis before you give up on that motor. If it's not knocking and smoking and it has oil pressure it's not done yet. The radiator cap shouldn't leak water,it should be going back into the recovery tank. Sounds like a cheap cap not sealing on the neck. Run the engine with the radiator cap off and look for little bubbles coming up into the neck. If it has head or head gasket leaks you will see them. If no bubbles check for airflow off the fan and listen for the fan clutch to engage and disengage. If the fan checks out the pull the radiator and look to see if it is clogged with debris. You can clean it with a water hose and jet nozzle hosing it from the rear(engine side). While you have the radiator out replace the water pump with a good quality new pump. After that if you think it is still running hot the replace the radiator. Over time they scale up inside and stop cooling the water.
Based on the questions you're asking I'd first recommend further diagnosis. If the engine does turn out to be bad, your best bet is to buy a crate motor. If you're really driven and want to have the experience of building it yourself, you can go that route, but it won't save you much money from a crate motor.
Hi, thanks for your response! To answer your questions in order
- that’s kind of the extent, I know I’m losing coolant because I tried bleeding it and it constantly had air bubbles in it even after an hour of running with cap off. It usually only shoots out from the cap after driving for longer than 10 or so minutes, and the temp gauge starts to run hot.
-oil quality is fine
- no white smoke or sweetness
- not pressure tested but I did get a block test done at a shop and it came back positive, but I obviously still have a problem.
- it is my current project car I’m hoping I can turn back into my daily driver
- I’m very versed in a lot of the rest of my truck, and I know have access to tools and a shop, as well as I have a Haynes manual for maintenance on my truck.
I see I see, yeah I wanted to do it myself for the experience and challenge as well, but what kind of diagnosis do you recommend should I take it somewhere or what tests should I run?
I did replace the water pump a few months ago, but I’ll try cleaning the radiator
I’ve taken it to a couple shops and they’ve said my truck is overheating and one guy said it could be the intake Manifold and the head gasket. But he didn’t give me anything beyond that and he sucked, but I do have the time, patience, experience, and space to do a rebuilt. But if there’s anything else I can test before fully resorting to that I’d like to try it. But as for the task of rebuilding, I’m up for it and I can handle it.
Intake manifold leaks do not create bubbles. It sounds like you may have a blown head gasket and/or a crack in a head. From what I've been hearing these modern heads crack from normal heat cycles over time. Not saying yours are but something to have checked if you pull the heads. If you don't have a lot of mechanical experience then a basic head job would be a good place to start. Most everything will only require normal hand tools,the only special tool you will need is a torque wrench. Whether you do this yourself or farm it out replace that old radiator. Kind of like buying insurance.
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