Diesel Maintenance Basics

[thesantoros]

Hi all! Just bought a bus a few days ago and it’s going to be a while before we can legally take it out on the road as an RV. Certainly, we plan on regular maintenance. The seller left the “maintenance due” sticker on it so we know when the next 5,000 mile oil change should be.

My question is two fold...

1. Other than regular maintenance at a service shop (every 5k miles / or every year) are there other considerations for properly caring for a diesel engine?

2. During the conversion process, how often should I start the bus? How long should I let it run? I’ve heard “idling isn’t good for bus engines” - but obviously I don’t have a lot of options until I can get it titled and plates for an RV.

[CHEESE_WAGON]

Idling isn't good for any engine, but sitting without running is worse. Engine should be run and trans should be put in forward and reverse gears occasionally when sitting without being driven. Run long enough to reach operating temperatures, short-cycling is hard on batteries, especially in cold weather.

Also, verify manufacturer's recommended service interval for your engine. 5000-7500 sounds like a typical gas engine interval for synthetic oil. Diesel oil is different and diesel engines require different intervals. Another thing, keep fuel tanks full to prevent condensation forming in the fuel, and keep an eye on filters and water separator. Diesel 911 and Diesel Kleen is good to add to the tank to prevent gelling.

[Shamoke]

If your bus has a high idle feature then you should use it when you are running it up to temp. If the oil is cold say below 35 degrees then you need to run the engine at slow idle for a minute to let the oil circulate and then put the high idle on for the rest of the maintenance run. Low idle rpm's on a diesel engine causes the engine to soot up and the cylinders to "wash" in fuel meaning scaring of the cylinder liners and excessive ring wear. This is why a high mileage diesel engine with average hours on it is preferable to one with low miles but high hours. There is no reason not to get 1 million plus miles on a modern diesel engine if they are properly run and taken care of.

[thesantoros]

Originally Posted by Shamoke

If your bus has a high idle feature then you should use it when you are running it up to temp. If the oil is cold say below 35 degrees then you need to run the engine at slow idle for a minute to let the oil circulate and then put the high idle on for the rest of the maintenance run. Low idle rpm's on a diesel engine causes the engine to soot up and the cylinders to "wash" in fuel meaning scaring of the cylinder liners and excessive ring wear. This is why a high mileage diesel engine with average hours on it is preferable to one with low miles but high hours. There is no reason not to get 1 million plus miles on a modern diesel engine if they are properly run and taken care of.

I do have a high RPM idle feature, so I will definitely use it. Thanks!

[Shamoke]

Originally Posted by thesantoros

I do have a high RPM idle feature, so I will definitely use it. Thanks!

Your welcome. Remember, diesel engines are designed to work hard and be under load, they rather enjoy it in fact. Don't be gentle with a diesel engine, make it earn it's keep, that's how they are designed.

[thesantoros]

Originally Posted by CHEESE_WAGON

Idling isn't good for any engine, but sitting without running is worse. Engine should be run and trans should be put in forward and reverse gears occasionally when sitting without being driven. Run long enough to reach operating temperatures, short-cycling is hard on batteries, especially in cold weather.

Also, verify manufacturer's recommended service interval for your engine. 5000-7500 sounds like a typical gas engine interval for synthetic oil. Diesel oil is different and diesel engines require different intervals. Another thing, keep fuel tanks full to prevent condensation forming in the fuel, and keep an eye on filters and water separator. Diesel 911 and Diesel Kleen is good to add to the tank to prevent gelling.

I think the seller left the owners manual, I have to remember to grab it to read through (the bus is not parked at my place).

I have heard people talk about the water separator, but I don’t know exactly what that means. 😬 I’ll do more research into what to look for in both the water separator and the fuel filters, anything you can add here will be much appreciated for me (and hopefully for others in posterity).

The gas tank is at 7/8ths right now, the closest gas station to where it’s parked does have diesel and is less than a mile away, maybe I’ll make a run to top it off this weekend. I’ll look into the additives, I’ve heard of both of those from scrolling the forum but I haven’t purchased any.

[CHEESE_WAGON]

Originally Posted by thesantoros

I do have a high RPM idle feature, so I will definitely use it. Thanks!

Let the engine warm slightly before doing so. Cold oil, cold engine and fast idle can do a lot of damage. Once the temp gauge begins rising (140+ degrees), the oil should be warm enough to use the fast idle feature.

Water separator is usually a see-through filter housing with a drain valve on the bottom. Water is heavier than diesel and will settle to the bottom, allowing it to be drained off without introducing air into the system. You can usually tell the difference between the water and diesel by looking at it. If you see a consistent color with no line separating two slightly different colors, you're good, if you see a line seeming to separate two liquids, you should drain the bottom liquid out. Easy peasy.

Filter housings should be filled / primed with fuel prior to startup after replacement. Most will have a little plunger-style pump in the lines or in the filter housing.

[thesantoros]

Originally Posted by CHEESE_WAGON

Let the engine warm slightly before doing so. Cold oil, cold engine and fast idle can do a lot of damage. Once the temp gauge begins rising (140+ degrees), the oil should be warm enough to use the fast idle feature.

Water separator is usually a see-through filter housing with a drain valve on the bottom. Water is heavier than diesel and will settle to the bottom, allowing it to be drained off without introducing air into the system. You can usually tell the difference between the water and diesel by looking at it. If you see a consistent color with no line separating two slightly different colors, you're good, if you see a line seeming to separate two liquids, you should drain the bottom liquid out. Easy peasy.

Filter housings should be filled / primed with fuel prior to startup after replacement. Most will have a little plunger-style pump in the lines or in the filter housing.

Thanks! I’ll look at these things next time I’m at the bus. The seller checked all the fluids and actually topped off the brake fluid for me right before we rolled out of his parking lot - so I have good confidence we’re good in the fluid department right now. (Also noting I might need to pay attention to the brake fluid in case there is a leak.)