When do I replace...
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Junior User
Joined: Jan 2004
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From: Sierra Nevada Mountains
When do I replace...
I just bought a 94 Bronco with 180k miles on it. It has a 302 5.0L. It runs fine right now, but I was wondering how to know when it is time to replace it. Hopefully there are some signs before I blow up on the freeway...
When it does come time, I was thinking of just getting a crate engine. Does anyone know how much it would cost for a mechanic to put it in (labor-wise)? And how big of a job is it? I just replaced a head gasket on another car of mine and it went fine. It was really hard though... What are the chances I could do it myself without messing everything up?
When it does come time, I was thinking of just getting a crate engine. Does anyone know how much it would cost for a mechanic to put it in (labor-wise)? And how big of a job is it? I just replaced a head gasket on another car of mine and it went fine. It was really hard though... What are the chances I could do it myself without messing everything up?
Junior User
Joined: Jul 2005
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From: Eglin AFB
when you compression starts to fail and you have really low oil pressure that cant be resolved by a new oil pump.
on that not the 302 is a really good motor. i have seen them with well over 300k on them. with that said take care of her and you wont have to replace her for a while
on that not the 302 is a really good motor. i have seen them with well over 300k on them. with that said take care of her and you wont have to replace her for a while
Freshman User
Joined: Sep 2005
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That is kinda a hard question to answer I think sometimes they just let go but keep changing the oil in it 3,000 miles I know some that change it more on often with higher millage vehicles. But I guess if things start leaking like oil pan gaskets stuff like that starts leakin u could pull the motor and just see what things look like . But I have saw 302 and 351w go for 200,000 to 300,00o or better just take care of it. Now for changin motors that would have alot to do with do u have a places that has all the tools like Cherry picker, jackstands and a nice building with a good conrete floor and even a buddy that could help u that second person makes a differents sometimes? all that stuff for me is a must to do any major jobs like that Dustin
Post Fiend
Joined: Nov 2001
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From: Topsfield, MA
An engine failure can happen at any time - engines throw rods - they crack blocks - ^#@$ happens.
For an old motor - it comes down to compression and oil pressure like the other's said...but I'll add alil.
When oil pressure is low at hot idle, but normal at all other times - the engine is close or ready for rebuild. When oil heats up it thins out and when this happens on a worn engine, the gaps and spaces in the worn bearings cause a loss of pressure. Normally, the pressure is about 15-20psi at idle while warm, it'll drop to single digits when the engine is getting close to rebuild time. Changing the pump will not help.
Also, as engines run the cylinder walls and rings wear and begin to loose compression. Low compression will make the engine burn oil and have poor power. Once this becomes unsatisfactory it's time to rebuild or replace. You'll notice the engine just doesn't have the grunt anymore and when enough is enough it's time to go...
For an old motor - it comes down to compression and oil pressure like the other's said...but I'll add alil.
When oil pressure is low at hot idle, but normal at all other times - the engine is close or ready for rebuild. When oil heats up it thins out and when this happens on a worn engine, the gaps and spaces in the worn bearings cause a loss of pressure. Normally, the pressure is about 15-20psi at idle while warm, it'll drop to single digits when the engine is getting close to rebuild time. Changing the pump will not help.
Also, as engines run the cylinder walls and rings wear and begin to loose compression. Low compression will make the engine burn oil and have poor power. Once this becomes unsatisfactory it's time to rebuild or replace. You'll notice the engine just doesn't have the grunt anymore and when enough is enough it's time to go...
More Turbo
Joined: Jun 2004
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From: Sweden
Well there's a lot to worry about other than just "the engine" wearing out. Timing chain is a big one, you wanna check that. Losing that sucks, it's pretty long job to replace. When it comes down to it, timing chain, water pump, fuel pump, fuel pressure reg, thermostat, alternator, idle air control valve, TPS, tranny, radiator, etc will be much more likely to leave you stuck on the road than the 302 itself just wearing out. Oh and I've had a stuck brake piston and a wheel knuckle break apart so it couldn't hold the brake (different occasions).
Just mentioning that since it's easy to focus too much on engine age and wear when the surrounding essentials are the more likely problem.
Just mentioning that since it's easy to focus too much on engine age and wear when the surrounding essentials are the more likely problem.
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Junior User
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From: Sierra Nevada Mountains
Ok. Thanks. I'll keep all that in mind. It sounds like that may be happening to my other car (same mileage but it's a chevy...). The oil light comes on when I am down shifting, stopping, and idling. However, I checked the cylinder walls with my fingernail to see if their was a notch (when I was changing the head gasket). It seemed like it would have lasted a little longer.
My uncle is building a garage at his house. I thought I would probably go there to do it. But now... I'll definitely wait and see what happens... now that I know the engine won't just decide to fall onto the pavement, and blow my cover when I'm trying to look cool.
My uncle is building a garage at his house. I thought I would probably go there to do it. But now... I'll definitely wait and see what happens... now that I know the engine won't just decide to fall onto the pavement, and blow my cover when I'm trying to look cool.
