Camshaft lobe repair ? M130.923 - PeachParts Mercedes-Benz Forum

1971 250/8 · #1 03-22-2019, 07:18 PM

Hey guys, anyone have experience repairing a flat lobe by welding it up, grinding it to specs? Looking for a shop that does this in California.

Im doing a rebuild on M130v engine, I6, M130.923

The camshaft is in great shape except for one lobe (position one) has lost about 1/4” in height on the point side where it is flattening out.

Tony H · #2 03-22-2019, 08:38 PM

I would look for camshaft grinders/repair. There are shops that can spray weld the damaged lobe and regrind it but I'm not sure where they would get the profile from when they grind it. Obviously you will need new cam follower(s). You might find a good, used camshaft with matching followers in a dismantler but I suppose you have already been that route. Are you rebuilding with new pistons or reusing the existing ones? Insure you take your block and pistons to a good machine shop to have the cylinders honed (not a ball hone) so they can take the taper out. Even if you see crosshatch there is still going to be taper which will keep you new rings from sealing properly long term.

97 SL320 · #3 03-22-2019, 10:02 PM

Having the cam repaired will be $$ compared to finding a used one.

The other issue is the cam grinder will need a profile master in order to regrind.

Not that I'd recommend it for anything I cared about, I have welded up cams with a MIG welder then hand ground / filed to shape in order to make a couple of engines " work " . These were overhead cam engines and there was an unworn portion on the edges of the lobe to provide a profile. And yes, I left the cam in the engine during the process.

Tony H · #4 03-23-2019, 12:13 AM

Wow-you're my new hero.

barry12345 · #5 03-23-2019, 08:54 AM

Not uncommon as I thought some of those cams where soft towards the front lobe. May have to ask around but I have had lobes restored and ground correctly years ago. On those engines. Inspect the followers as well as I remember they can wear through the surfaced hardness and it is quite visible when they do.

Because of todays costs I would put a request on parts wanted. So many 114s rusted out there should still be some good cams and rockers out there. I am sure you know to request them numbered from front to back. Remember to test all your valve lash adjusters with a torque wrench for minumun resistance.

I have two good m130 engines. They are just too good to part out. One with a flywheel clutch and four speed. The place I used to build and machine the cams was in Montreal Canada. I am pretty sure they are still in business. I live 600 miles away.

I just know the cost is no longer fifty dollars. The classic center may point you to a place that has the profiles for these cams. If others that post have no ideals. How common was your issue? On one of the spare engines I have there was a new cam rockers and towers present

They made a lot of those engines so the wrecking yards might be your best option as well.

1971 250/8 · #6 03-23-2019, 08:30 PM

Hey guys, thanks for the great responses. I've posted a few pictures, the worn lobe is position #1. (The rocker arm contact area looked good)

I'll ask my local machine shop about the spray welding camshaft repair. The other lobes look pretty good, I still need to measure them.

As for the head, today I removed rockers and springs, over the next few days I'll be spraying the manifold studs with penetrant. Gasket surface is flat as plate glass, as is the block... pretty happy about that.

I'll be replacing 2 bad pistons, all rings, seals, etc.

Block is submerged in electrolysis tub to remove as much rust as possible. Machine shop will measure the bores but I'll most likely ream the lip and do the 45 degree crosshatch myself.

I'll update this issue on my rebuild thread after the machine shop weighs in.

vandor · #7 03-27-2019, 11:27 PM

Delta Cam in Washington state has been around for a long time and they do weld and grind lobes for hi-po applications, so I assume they could repair yours be reading one of the other lobes and grinding that profile onto your cam.
As others said, a used cam should not be that hard to find.

Idle · #8 03-28-2019, 12:50 PM

Quote:

Originally Posted by 97 SL320

Having the cam repaired will be $$ compared to finding a used one.

The other issue is the cam grinder will need a profile master in order to regrind.

Not that I'd recommend it for anything I cared about, I have welded up cams with a MIG welder then hand ground / filed to shape in order to make a couple of engines " work " . These were overhead cam engines and there was an unworn portion on the edges of the lobe to provide a profile. And yes, I left the cam in the engine during the process.

I have been the 'weld up, grind down' route on some farm equipment. It will run when you are finished but it is of course not the best way to do things. It depends on the application.

This was some farm machinery that had to get a crop out of the field and the nearest place with the correct part was 550 miles away.

So can this be done? Sure. The thing to remember here is this is a terrible way to do things if you are expecting perfect results. If you need the engine to run, poorly, this works. I don't know for how long because we ordered a new cam the next day and installed it a week later.

barry12345 · #9 03-30-2019, 03:22 PM

I would not be a fan of spray weld. As I mentioned Mercedes messed up the hardening process I suspect near the front of those cams. So many will have replacement ones installed.

The wreckers and junk cars are your best bet.

Sugar Bear · #10 03-30-2019, 04:03 PM

It is best to ream the ridge before removing pistons that will be reused. Removing the ridge first reduces the chance of breaking a ring land on the piston.

Good luck!!!

bcbens@embarqma · #11 04-19-2019, 07:50 PM

Check these folks out. https://mercedesengines.net/ They are in SoCal. Canoga Park, I think. I purchased a rebuilt cam from them a few years back for my M130.923 My old cam was repairable, so I think my cost was less than $300 final cost after core deposits. Could be wrong on the cost.

Benz Dr. · #12 04-21-2019, 02:54 AM

Quote:

Originally Posted by Sugar Bear

It is best to ream the ridge before removing pistons that will be reused. Removing the ridge first reduces the chance of breaking a ring land on the piston.

Good luck!!!

Don't do that. It won't gain you anything. If you break lands they were already broken or you're careless. On something that worn it won't matter that much anyway.
If the cylinder is 86 mm it's that size everywhere except where it's worn. The piston will come out. Clean the top of the cylinder first and then use some oil so it will slide out easier.