# motor went boom



## mp4life23 (Apr 28, 2010)

Well guys i was driving down the road and i got on her a little bit and she started making a really funny noise.It would only make the noise above a certain rpm and when the engine warmed up Come to find out the oil pump screen came off and no oil was being sucked up I spun a rod bearing the only one that's loose is the very back rod bearing. 

what should I do ?


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## Rukee (Feb 8, 2007)

If the crank is not damaged you could throw some rod and main bearings in along with a new high volume oil pump and screen. Then after you put the screen on the pump weld it in place with a wire feed welder.
If the crank is damaged, then it needs to come out and be machined/turned.


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## mp4life23 (Apr 28, 2010)

If a rod is bad also, can i just change that rod or do I have to change all of them


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## Rukee (Feb 8, 2007)

More then likely the rod bearing is the only thing damaged. If the rod itself is bad I'd guess the crank is wiped out as well.


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## ALKYGTO (Mar 29, 2010)

^^I agree. I had this happen to me on a 340 small block Plymouth. I just happened to let a friend borrow it and he pulls up into my driveway with it and says " You've only got 10 psi of oil pressure", I just about came unglued that he did'nt pull over right away. Fortunately I could change out the bearings in the car. Sucks either way though. 

Some on here may disagree, and you may have reservations, but even if the crank has minor scratches, you may be able to polish them out with super fine (600 grit emory paper). You should'nt be able to catch a fingernail on any scratches. 

Good luck!


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## ALKYGTO (Mar 29, 2010)

How about some pic's of your car? Looks kinda cool in your avatar. :cool :cheers


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## Thumpin455 (Feb 17, 2010)

I flattened the upper bearings in a 400 with too much compression, it didnt spin the bearing it just flattened it. The rod was ok, but the crank was badly scored, so I pulled the crank leaving the heads and pistons in the block, and had it ground. Put it back in with new bearings and oil pump and its still together.

It depends on how bad things are hurt as to what you will have to do. Sometimes you can get away with just throwing some new bearings in, sometimes you cant. If it spun in the rod it will need to be resized or replaced. That means pulling the heads to replace/repair both rods off that journal, because both of them will be done if that journal is starved of oil.

Think of it as an opportunity to throw a stroker kit in it.


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## mp4life23 (Apr 28, 2010)

Here you go


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## ALKYGTO (Mar 29, 2010)

Nice, I like that in gold. I actually like the look of that flat black hood, murder out the wheels and get rid of the green stripes and it would be pretty wicked looking. 

Do you have the motor out of the car?


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## freethinker (Nov 14, 2009)

mp4life23 said:


> Well guys i was driving down the road and i got on her a little bit and she started making a really funny noise.It would only make the noise above a certain rpm and when the engine warmed up Come to find out the oil pump screen came off and no oil was being sucked up I spun a rod bearing the only one that's loose is the very back rod bearing.
> 
> what should I do ?


when a pontiac has rod problems it usuall spins the rod bearings in the rods. if any of the bearings spun in the rod that piston must come out and the rod muct be replaced or resized.
at the very least you are looking at pulling the crank and turning it undersize. i doubt you will be that lucky. its sounds like you did major damage that will require a crank and rods. its time for a complete engine disassembly.


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## mp4life23 (Apr 28, 2010)

i got the motor out of the car now. im just on a very limited budget


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## 740tank (Mar 23, 2009)

lol man I had the same problem on my 04 gto low oil. And as soon as I heard it knocking i parked it. it would only knock at about 2300 rpm very consistant guaranted every time. I took the motor out, and luckely i didnt drive it like this but about 20 miles and all it did was mess up the bearings and scared the crank shaft a little. and they just polished or buffed the shaft for like 75$ bought new bearings and was on my way


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## jetstang (Nov 5, 2008)

Find a good machine shop, take the crank and rods to them and have them fix what is hurt. I put a new bearing in mine back in the day and it still knocked, and I sold the car dead. Now, I know, this is the time to put it back together correctly, waste of time to try to just replace a bearing.


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## ALKYGTO (Mar 29, 2010)

Throw a Pontiac 350 from the boneyard in there so you can drive it while you build the snot out of your 400 over the winter. 

Then you can ask Santa for a stroker kit.


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## mp4life23 (Apr 28, 2010)

how can you tell if a rod is bad what do you measure are there any signs of it being bad


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## Rukee (Feb 8, 2007)

mp4life23 said:


> how can you tell if a rod is bad what do you measure are there any signs of it being bad


When you take the rod bearings out, if the rod bearing shows signs of spinning, or turning inside the rod, then the rod needs to be re sized. If the only damage is to the inside of the bearing and the bearings are still held in tight to the rod then you should be fine. It's when that bearing starts spinning inside the rod that does damage. So, inside of the bearing damage is 'okay' (as long as the crank is good), outside bearing damage is tear down time.


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## mp4life23 (Apr 28, 2010)

What about stretching?


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## Rukee (Feb 8, 2007)

Unless you're pushing 7-9,000rpms, you shouldn't need to worry about the rod stretching.


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## mp4life23 (Apr 28, 2010)

what kind of oil are you guys using in your 400's


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## Rukee (Feb 8, 2007)

I use only Valvoline Racing 20w-50. Has the additive for the flat tappets.


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## mp4life23 (Apr 28, 2010)

The guy who built the motor said to use 15 40 rotella what do you think I should use


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## geeteeohguy (Feb 2, 2008)

That's what I use. I recommend a ZDDP additive as well.


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## 68greengoat (Sep 15, 2005)

I'm using it as well.......


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## jetstang (Nov 5, 2008)

Machinist told me to run a bottle of assembly lube in every oil change on solid/hydraulic cams.


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