Changing crankshaft bearings with the engine in the car.

[413]

What about the cam bearings? They're just as old/ wore as the crank bearings.

I bet the cam bearing wear is half as much or less since it turns at half crank speed, and has a constant load.

Crank bearings do much more work than cam bearings.

You'll be fine doing it in the car, old bearings come out easily. Change the oil pump while you are in there with a new standard volume pump.

 

[Kern Dog]

the gargantuan pain in all nine assholes of laying on the ground with **** dripping and dropping on your face while cussing and fussing on this job aside... what happens when you're done and (insert sing-songy voice) the oil pressure's still low?

while it's likely just the bearings are beat down, the possibility does exist that the crank could be pooched as well.

or maybe the oil pump is waxed ***...

i say throw some 50 weight at 'er and let it rip, see what time it is.

but if i'm doing mains, i'm doing rods-- in for a penny, in for a pound. what's another few hrs to yoink a motor at that point for the ease of working standing up.

I would be doing it standing up.

What about the cam bearings? They're just as old/ wore as the crank bearings.

Cam bearings don't see reciprocating wear, they see rotational. It has been my experience that crank bearings see far more wear than cam bearings.

Also, consider what some have said. If the bearings and or crank need help, what about the cam bearings? What about the camshaft itself? The lifters? How sloppy is the timing chain? What about the rings? If this is a car you're gonna sell, then shyster it up and unload it. If you plan to keep it, you might want to rethink it.

When I sell something and I want top dollar, I do NOT want it coming back to haunt me. I make the car as mechanically sound as I can just to protect myself from looking like a liar and a cheat.
The camshaft is probably fine. all the rocker arms are secure with no play. The engine idles and runs great.
I will change the oil and try another oil pressure gauge first.
Thanks!

 

[abdywgn]

IF this is a "I wonder what this would do" experiment, pull one bearing out of the cap. If std. size, get a set of .001" oversize. or plastigauge and see what clearance is.
please disregard, just typing with out thinking.

 

[ProjectBazza]

I would bend up a cotter pin to slip into the oil hole, funny angle thing and just rotate the crank.
The cotter pin "flukes" laying across the bearing surface would just push the shell around till it'd pretty much fall out when nearly all the way around.
Just lay the new shell on the clean/lubed crank surface, finger pressure to get it started, the cotter pin/rotate shaft till you can engage the "tab".

Not my favorite job, hoist helps.
@Kern Dog

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That's the exact same method I used, twice, on some old trucks, about 30 years ago or so. Maybe we learned about this from the same source! (Hot Rod mag, perhaps?)

Regardless, I know the OP has a hoist, but I hate working over my head, so if thicker oil isn't an option, if it were up to me I'd pull 'er.

 

[junkyardhero]

I would be doing it standing up.

View attachment 1716305271

well, la dee da! look at you mister fancy pants!

kindly excuse me while i go writhe around on my tijuana creeper™ like a peasant

all kidding aside, that take some of stink outta the job. i'd mark it a pain in three dickholes with a lift.

 

[Kern Dog]

I bought the lift in 2015. I built the shop in 2006 with the intention of installing a car lift.
I am still fully capable of "flat back" work but this is so much better. I lose perspective of what is the left and what is the right when I'm laying down. Standing while working is a lot easier.

 

[junkyardhero]

I bought the lift in 2015. I built the shop in 2006 with the intention of installing a car lift.
I am still fully capable of "flat back" work but this is so much better. I lose perspective of what is the left and what is the right when I'm laying down. Standing while working is a lot easier.

i was just goofin' about the lift. i have one too, and while it's sooo much nicer to work standing up, it seems like i've always got a car on it and one underneath torn apart and unmoveable and two parked up land locking evertything. which, now as i type that out sounds more of a "me" problem than i'd care to admit.

pro tip: if you put your hands out in front of you, the one that makes an L with your index finger and thumb is not your right.

 

[Max1196]

Cam bearings don't see reciprocating wear, they see rotational. It has been my experience that crank bearings see far more wear than cam bearings.

Ok.

 

[Kern Dog]

Of all the engines that I have torn down to rebuild, very few had cam bearings worn much. The ones above didn't wear, they rotted from contamination. Bearings don't flake and chip apart from wear.

 

[junkyardhero]

I have heard/read that magnum cam bearings wear more than anticipated ??

i mean, think about what they came in: trucks (mostly) and what gets abused more than work trucks? more likely to neglect OCI and maintenance? (*coughs* besides rental equipment *coughs*)

the "flaking" of cam bearings has also been (loosely) linked to the acid/acid by products in modern motor oils, namely synthetics-- which again, goes to extended, missed or ignored OCI's.

so, little wonder the cam bearings are pooched in a lot of magnums.

 

[Inertia]

That's the exact same method I used, twice, on some old trucks, about 30 years ago or so. Maybe we learned about this from the same source! (Hot Rod mag, perhaps?)

Very well could have been, I used that method before my apprenticeship.
We gained mosta our early knowledge from the monthly magazines, and adapted that to whatever make we were working on.

Personally, I'd run 20/50 like I do my high mileage Jeeps. 300k, 3 of em, - knock like hell for a coupla seconds every morning , - for years.
Cheers

 

[Kern Dog]

The nearby dump has a recycling facility where people can take stuff that others “recycle”. Sometimes it is spray paint, bug killer or cleaners.
Sometimes it is oil still in unopened containers. There will be some that suggest that you don’t use old oil but my thought is… for a stock vintage engine not built for high performance, it will be fine. It is coming from a sealed container and it was made with less detergents and likely has some zinc in it.
Look at modern oil:

I don’t have the info right in front of me but I read an article that laid out a timeline for when the detergent packages were ramped up and zinc was phased out. See where the blue bottle has an API rating of SN plus? That is the highest rating so this oil is great for newer cars but not so much for the classics. That article stated something about the SJ series still having some zinc but less detergent. Lower alphabet letters indicate older oil with less detergents and more zinc.
I got 10 bottles of classic Castrol.

See the API rating?

This stuff is much better for classic engines. Get ready for one better!

Remember that stuff? I remember the TV ads for it back in the 80s. Someone had 6 unopened bottles at their place for years before it was brought to the dump. Check out the API.

Backing up a bit, here are two bottles of Castrol. Old on left, new on right.

Remember, the old stuff was API SF.

Again, fine for newer engines but no zinc for us classic car guys.

4 1/2 quarts of vintage ARCO Graphite and….

55 PSI at cold fast idle. 20 at hot idle in gear. That is plenty good enough to forego a bearing swap. The old oil looked clean but drained out like water even with the engine still sort of cold. I only ran it long enough to move it to the other room.
Score!

 

[Darter6]

I would be doing it standing up.

Now your talking !

capable of "flat back" work

Not for me anymore. The problem is not getting down,it's trying to get back up again !!! I have a hard time doing ups....