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2008 MP8 Camshaft and Roller Out

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Got a MP8 exhaust roller and camshaft on #1 cylinder, camshaft will have to be replaced, should you replace all 24 roller rocker arms or just the one, mack parts said rollers not replacable. Tiny bits of metal around #1 where the cam roller ate into the camshaft. Should rod and main bearings be checked or will the filters catch that.

Thanks

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I replace all the exhaust rocker arms. The filter system is good but I would probably check the rods and mains to be on the safe side. Also if it is bad enough the matal can catch in the oil cooler and come out later.

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If it were warranty then only the damaged components would be replaced (camshaft and bad rocker arm) including oil and filters. Most of the metal will be in the trough below the damaged rocker/cam journal. I would make sure it is cleaned out. Other than that, if it were mine I would reuse as much as possible. Inspect all the rocker arm rollers, if you can catch your finger nail on a mark/spot then it should be replaced. Inspect the camshaft journals, if there is a questionable spot on the journal that you can catch you fingernail on but the rocker arm roller that rode on that journal appears to be damage free I would replace the rocker arm anyway to be safe.

As I said earlier, most of the metal from the damage is caught in the oil trough below the damaged journal(s). Some metal may make it to the oil pan but rarely, if ever, have we had to check main bearings due to a camshaft failure. Just my $.02

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Turckster On the Etech and e7 we allways replaced cam and all lifters. Under warranty mack don't replace all rollers with a new camshaft? This is the first camshaft we put in an MP8 engine. The cam and the exhaust roller are all chewed up on #1 exhaust, if under warranty mack don't replace all it must be acceptable. Thanks

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Warranty wise, on the etech engines w/ceramic lifters only the failed lifters were to be replaced, all others were reusable. It could be the same for steel roller lifters as well, I don't remember. Years ago when the etech cams first started failing we replaced all lifters but those were the steel roller type and everything came in complete kits including cam bearings. On the e-7 cams you had to replace all the lifters because the wear pattern between lifter/lobe. When we replace camshafts out of warranty on etech engines we prefer to replace all lifters, with customer approval.

The warranty criteria on mp engines is replacement of damaged components only, if you can catch your fingernail on what looks like excessive wear on a rocker arm roller then it should be replaced as well. We use that same criteria on out of warranty engines as well. The only time I would replace all the exhaust rocker arms is if they were an old design that has been phased out.

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Turckster one more question. Checking the price of the J44514B camshaft aligment tool and it is over 1500.00. Only have 2 MP engines running and rest are E tech's. Planning on getting out of trucking at the end of year with new electronic logging coming on and trucks getting old, a good time quit. We replaced the head off the other truck a couple of years ago and we pulled the camshaft out with the gear on and marked the teeth and put it back in the same place and checked gear play and it was ok. If we mark the gears and put the gear back on the new cam in the same place with engine on tdc will it work? What is the purpose of this tool, does it do fine timming ? I found SB 213-061 and it shows we have early exhaust, inlet, and injector rocker arms and should be replaced. Thanks

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The purpose of the kit is to make sure that the camshaft is exactly in time since it is so easy to be off by one tooth. The proper procedure is to replace a cam on a MP engine is to removed the rear upper cover, remove the cam vibration dampener and drive gear. The kit has the tools to check camshaft alignment to be sure it is in proper time plus to measure camshaft gear backlash. You can replace a camshaft without using that tool by simply removing the cam bearing upper caps, unbolting the cam from the gear/dampener, sliding the cam towards the front of the engine and lifting it out. Reverse to install but you have to be careful to not move the cam gear too much. You don't want to have the gear jump a tooth out of time. Before doing any of this, make sure the engine is set at zero on the flywheel and the cam TDC mark is between the #1 cam cap marks. When replacing a cam the TDC mark should be in the same place from old to new.

If the gear were to jump out of time, you would have to remove the back upper cover. Make sure the engine was set on zero at the flywheel, install the cam where the TDC mark was between the #1 cap marks, installed the drive gear. There is timing marks on the cam gear and an alignment hole in the head (this is where the special alignment tool would go if you had the kit). As long as the timing marks are between the hole then chances are you're ok with the timing.

If the cam gear were a tooth off, lets say advanced, usually the engine runs fine, but will eventually set a cam position fault. Same with a tooth off but retarded, the engine will be slightly sluggish but run ok none the less, eventually it will get a cam position fault as well. Sometimes it could take as long as several months for a fault to set.

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I doubt anybody uses that alignment tool anymore, I've seen reman engines come back weeks later with the lightning bolt on and found the cam a tooth off.

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I've heard they are $400 each. If it ain't broke......

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On 1/24/2016 at 10:01 AM, Macktech689 said:

I doubt anybody uses that alignment tool anymore, I've seen reman engines come back weeks later with the lightning bolt on and found the cam a tooth off.

^689  is on the money there !Yup bogus tool in my mind ! Mark your gears when u pull it back in the same spot when u assemble!

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