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Hi Lionel and group,
In the former group and this group I have posted about the rear camshaft bearing particularly in P series engines. These engines have a different oil base on them from the B series engines in that the dipstick tube is a larger diameter and has a seal where the tube connects to the oil base with a bracket holding the tube in place. The dipstick itself has a cap with an o ring seal. The problem with the tube seal is that they fatigue and can leak oil as this seal is below the static oil level when the engine is not running. The other problem is that the sealed dipstick cap causes oil to draw up into the tube as the engine cools after shut down. If the oil level is not correctly checked, a low engine oil level can happen with the operator thinking that the oil level was within operating limits. These engines of all that I have worked on are the most sensitive to operation with low engine which causes internal damage. Although these engines have a pressurized lubricating system, not all moving/rotating parts are pressure lubed, the tappets, valves and the rear camshaft bearing are splash lubed while the engine is running. with a low oil level in the engine, the splash of oil to these areas is decreased. The early P218 that was in my 1989 4018 was very noisy with camshaft side slap at idle. I did a decarb and a valve adjustment on this engine and wasn't able to repeat the valve adjustment when turning the engine over by hand back to TDC. When I tore this engine down I found the rear camshaft bearing worn in a side to side oval pattern. Prying on the camshaft bearing a little cause it to come out in two pieces. The camshaft measured out to be still within specs and not oval. Onan has changed this bearing which is supposed to be stronger and allow oil to enter the bearing easier. The problem with replacing this bearing is that a major teardown is needed just to get to it and while you are in there, you may as well do a major overhaul as there is always something else that should be addressed.:cool:
 

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Discussion Starter · #22 ·
Hi Lionel and group,
In the former group and this group I have posted about the rear camshaft bearing particularly in P series engines. These engines have a different oil base on them from the B series engines in that the dipstick tube is a larger diameter and has a seal where the tube connects to the oil base with a bracket holding the tube in place. The dipstick itself has a cap with an o ring seal. The problem with the tube seal is that they fatigue and can leak oil as this seal is below the static oil level when the engine is not running. The other problem is that the sealed dipstick cap causes oil to draw up into the tube as the engine cools after shut down. If the oil level is not correctly checked, a low engine oil level can happen with the operator thinking that the oil level was within operating limits. These engines of all that I have worked on are the most sensitive to operation with low engine which causes internal damage. Although these engines have a pressurized lubricating system, not all moving/rotating parts are pressure lubed, the tappets, valves and the rear camshaft bearing are splash lubed while the engine is running. with a low oil level in the engine, the splash of oil to these areas is decreased. The early P218 that was in my 1989 4018 was very noisy with camshaft side slap at idle. I did a decarb and a valve adjustment on this engine and wasn't able to repeat the valve adjustment when turning the engine over by hand back to TDC. When I tore this engine down I found the rear camshaft bearing worn in a side to side oval pattern. Prying on the camshaft bearing a little cause it to come out in two pieces. The camshaft measured out to be still within specs and not oval. Onan has changed this bearing which is supposed to be stronger and allow oil to enter the bearing easier. The problem with replacing this bearing is that a major teardown is needed just to get to it and while you are in there, you may as well do a major overhaul as there is always something else that should be addressed.:cool:
Hi Lionel and group,
In the former group and this group I have posted about the rear camshaft bearing particularly in P series engines. These engines have a different oil base on them from the B series engines in that the dipstick tube is a larger diameter and has a seal where the tube connects to the oil base with a bracket holding the tube in place. The dipstick itself has a cap with an o ring seal. The problem with the tube seal is that they fatigue and can leak oil as this seal is below the static oil level when the engine is not running. The other problem is that the sealed dipstick cap causes oil to draw up into the tube as the engine cools after shut down. If the oil level is not correctly checked, a low engine oil level can happen with the operator thinking that the oil level was within operating limits. These engines of all that I have worked on are the most sensitive to operation with low engine which causes internal damage. Although these engines have a pressurized lubricating system, not all moving/rotating parts are pressure lubed, the tappets, valves and the rear camshaft bearing are splash lubed while the engine is running. with a low oil level in the engine, the splash of oil to these areas is decreased. The early P218 that was in my 1989 4018 was very noisy with camshaft side slap at idle. I did a decarb and a valve adjustment on this engine and wasn't able to repeat the valve adjustment when turning the engine over by hand back to TDC. When I tore this engine down I found the rear camshaft bearing worn in a side to side oval pattern. Prying on the camshaft bearing a little cause it to come out in two pieces. The camshaft measured out to be still within specs and not oval. Onan has changed this bearing which is supposed to be stronger and allow oil to enter the bearing easier. The problem with replacing this bearing is that a major teardown is needed just to get to it and while you are in there, you may as well do a major overhaul as there is always something else that should be addressed.:cool:
Thank you very much it looks like that what I will have to do. This engine was abused before I got it so I suspect I have the same scenario you have. Thanks for your help!
 
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