superdave269

A friend of mine insist that I will need to replace my cam now that I have spun a rod bearing. He believes now that engine has pumped oil filled with metal in it the cam and lifters are shot. I think he is over thinking this. What do you engine builders have to say on this? Thanks

oldalaskaman

I agree with you, the cam pieces would have dropped into the oil pan and probably didnt make it past the oil pump screen or filter

Avette4me

I subscribe to doing the entire engine if I'm that far in...

DRIVESHAFT

I would say that your cam & lifters are most likely fine.
Just look them over while you have the engine apart.

1969Corvette

The metal mixed with the oil for sure how bad you won't know until you tear into it. I would flush the entire block,heads and every passage with kerosene to clean it out, Then start a rebuild,. The cam might be OK the lifters might have metal in them. I wouldn't chance it over a couple hundred bucks not worthe it and I am cheap.

drwet

The other thing to consider is the fact the big end of the rods spin very close to the cam. (Some closer than others.) If you spun a rod bearing that gets close to the cam it may have tagged the cam. Check the cam and it may be OK, but I tend to side with the guys who say replace the cam. If you've spun a rod bearing, you need a complete rebuild...If you're going that far, just replace the cam. Especially if its just a flat tappet cam. They're cheap. If you have a roller cam, I might think about keeping it.

Bagmup

This...

pauldana

And the scuffing of the piston walls don't forget... Once the shavings hit the oil... Big permanent damage starts..... EVERYWHERE

BKbroiler

What shavings and pieces everywhere? It's a spun rod bearing, not a flattened cam lobe.

pauldana

If there are no shavings he's good to go..... Just saying, if there is.... It's probably gone...

The op was worried about the cam.... What else would make you worried about the cam other than shavings?....

Op post:


superdave269
Can a spun rod bearing hurt a cam?
A friend of mine insist that I will need to replace my cam now that I have spun a rod bearing. He believes now that engine has pumped oil filled with metal in it the cam and lifters are shot. I think he is over thinking this. What do you engine builders have to say on this? Thanks

johnnyjaws

the oil filter more than likey caught it

hugie82

To factors come in play, how long did you run it with the spun bearing and if the engine was cold or had high oil pressure when bearing let loose.

The bypass valve lets oil pass the filter and that means you have metal partials throughout the engine if pressure was high enough (ie high pressure/HV oil pump.

If you ran it a long time, then the oil pressure dropped very low causing other damage. I can see a 383 in your near future

pauldana

if.... and im saying only if.... there are shavings in the oil..and i am not saying there are... again just going with original post. the oil splash alone will throw the contaminates everywhere... when a cam goes flat it just doesn't go peacefully to the bottom, the oil splash throws it up into the piston walls... its happened to me.. sucks.......... yes though, i agree... he has a considerably better chance of living through it with a spun bearing......


and what hugie82 said...

terrys6t8roadster

spun the rod brgs 3 summers ago at the track. [I guess this is what happens when you build the top of the engine with a stock bottom]. brg particles everywhere upon dissambly [ the heads were just coated]. Lunati cam & crower lifters, cleaned, inspected, had the machine shop who built the new short blk also inspect the cam & lifters AOK. reused them and have been for the past two seasons . shift lite comes on all the time at 7400rpm and all is well.

superdave269

Thanks for all of the relies. One of the reasons I was asking is the cam only has 100 miles one it. Classic rebuild the top end and the bottom end goes, UGH! A total rebuild is in order and machine shop work is ahead as I am sure the crank and rods will need to be cut/ resized. I have an original 454 car and want to keep the original engine so it will come out and be broken down and rebuilt.
I would hate to cheap out on only the cam just to find I need to replace it down the road, but if its OK I don't want to waste my money. Once we pull it I guess we will be able to tell a lot better.

4 speed

for what its worth, I just spun #'s 3 and 4 in my 73 350. due to a broken oil line and running the car out of oil.

any how, I dropped the pan in the car, replaced all rod bearing with stock , except 3 and 4. they are -.002. there was bearing material in the pan. I cleaned it out of course .

fresh oil and filter, ran it about 10 miles or so, then changed oil filter again. I did add STP oil with last change.
got good oil psi, and no noise.

this was on the cheap has I am out of work right now, but atleast I can still drive my car.

a rebuilt / engine swap is in the future, but this got me by.

Indiancreek

As long as you clean the block very well. The debris and hidden debris will damage the other and replacement bearings. You'll need to clean all your oil passageways before you put it back together.
This is yet ANOTHER while you're this far into it you may as well ???????.

If I were in your shoes, not knowing the miles on your engine, I'd take it apart and inspect the parts. rebearing it and replace the rod that had the spun bearing, turn the crank, replace the cam bearings. If the build was a low budget keep it running repair.

Not really, I'd have the block baked, bore and hone it, new cam, pistons and rings, recon the rods, balance the parts and recon the heads spend much more money, but have another engine that should last a long time and I would have confidence in.

Back to the original question, just having spun a bearing doesn't necessarily mean a new cam.

oldalaskaman

I like paldana's answer better then mine, shows a neat thought process

bpassmore

If there are questions, sample the oil-- go from there, it is cheap.

SuperBuickGuy

As an engine builder, I'd rebuild the entire motor - including replacing the cam. The oil filter does NOT filter all of the oil - it can bypass up to 70% of the oil if the filter is blocked (change your oil folks!) so it won't catch all of the shavings.

As a car flipper. Replace the bearing, change the oil and send the car down the road. If you feel like reducing your profit, dump some diesel through the motor (kerosene? at 10 bucks a gallon, no thank you).

but even as a car flipper - my conscience says, if it's a stone, stock car with no mods and everything else works fine - clean and replace the bearing. Otherwise, rebuild or replace.

However, in most cases, the rod knock is the result of someone driving miles with a bad bearing - so the crank is toast, and replacing the bearing won't fix the problem.... replacement only works when the motor rattles under load. If it rattles all the time - find a motor on Craigslist, then you can advertise "replaced motor with JDM motor" (lol).

I had a tractor with a rod knock (a 9N Ford), and I simply replaced the bearing despite a great deal of scoring (flatheads don't normally have filters)... I know who has the tractor, now 30 years later, and it's still running on that replaced bearing (I used a flap wheel to take the tops off the scoring - a precision one, of course)