Does the amount of leaks coincide with maintenance?

[The motor guy]

I have two diesel trucks. One an 07 and one a 99 model, both of which are cummins. The 99 was recently purchased and it has nickel sized oil drips where I park at night. The 07 which I've maintained and owned from day one is dry as a bone underneath. The 99 has no blowby so it's still in good shape mechanically I'd hope. Maybe the 07 just isn't old enough yet?

 

[The motor guy]

Also I don't notice any noticeable drop in fluid levels on the 99

 

[joekingcorvette]

I think it depends on the blanket history of a vehicle. For instance I had a Cadillac with the Northstar engine and everyone I talked to said they leaked oil once they were a couple years old. Old chevrolet engines always leaked and the newer ones are really tight. It just depends on the "leak history" of the type of vehicle you own. Sorry I can't help you more maybe someone else who has the same vehicle can help.

 

[The motor guy]

I think it depends on the blanket history of a vehicle. For instance I had a Cadillac with the Northstar engine and everyone I talked to said they leaked oil once they were a couple years old. Old chevrolet engines always leaked and the newer ones are really tight. It just depends on the "leak history" of the type of vehicle you own. Sorry I can't help you more maybe someone else who has the same vehicle can help.

Probably has more to do with engineering and gasket material

 

[Kurtatron]

Cars that sit leak at any seal that’s not RTV. So cam, main seals, valve cover gaskets leak if they sit for a long time without use. RTV doesn’t care if it’s been sitting idle.

 

[The motor guy]

Cars that sit leak at any seal that’s not RTV. So cam, main seals, valve cover gaskets leak if they sit for a long time without use. RTV doesn’t care if it’s been sitting idle.

Do they seal back up once the vehicle gets used again?

 

[cptbarkey]

There is little magic to oil leaks, and age is probably the #1 cause. Where is it leaking from?

 

[Kurtatron]

Do they seal back up once the vehicle gets used again?

Not really. You can use high mileage conditioner oil that swells the seals. But once you use that, you need to only use that kind of oil.

 

[Propflux01]

I would say age over maintenance, unless that maintenance is the actual cause of the leak.

 

[ElectroMechanoMan]

Check and see if the 99 has a road draft tube for crankcase ventilation. They will drip a small amount, especially after a long hard run.

 

[TeeCee]

Not always the case, my shop has gotten to the point we notate oil leak on a GM before we get underneath it. New ones, old ones...

 

[The motor guy]

Check and see if the 99 has a road draft tube for crankcase ventilation. They will drip a small amount, especially after a long hard run.

It does, but I question if that blowby tube is enough to make the oil pan of the engine oily all the way back to the trans

 

[ElectroMechanoMan]

The other place that has leaks on Cummins engines of that series is the accessory case gaskets. I had a leak on mine and it’s a sizable job to repair depending on if the leak is between the case and the block, or it’s just the outer cover that is leaking. Either way, the crank pulley has to be pulled. If it’s the back half, all of the timing gears have to be pulled.

 

[MSCH]

The other place that has leaks on Cummins engines of that series is the accessory case gaskets. I had a leak on mine and it’s a sizable job to repair depending on if the leak is between the case and the block, or it’s just the outer cover that is leaking. Either way, the crank pulley has to be pulled. If it’s the back half, all of the timing gears have to be pulled.

and if it is a B series or C series, its just about impossible to pull the cam without turning the engine up side down as the cam followers really interfere with removal of the cam.

 

[John105]

I want to say no. But, I wonder if it has ever, ever, been studied, where a fleet of vehicles began use at the same time, and then recorded when issues arised, and compared. Do all vehicles being to leak at a certain mileage, age, or is it random?

 

[t1snwrbrdr12]

I want to say no. But, I wonder if it has ever, ever, been studied, where a fleet of vehicles began use at the same time, and then recorded when issues arised, and compared. Do all vehicles being to leak at a certain mileage, age, or is it random?

Our Chrysler 3.6 pentastars are almost all leaking way early in my opinion. I’ve done oil coolers and radiators for the past couple years or more. These are all 2018 model years, mileage about 10k to 50k or so. Highest mileage one I’ve worked on is a hair under 100k because it makes longer trips every day.

These are all supposed to receive maintenance at 6 months. Maintenance up until this last year meant an oil change and look over…fix whatever you find…it’s a fleet, we keep them safe and that’s about it. Later they’ve come to think even an oil change at 6 months is not necessary, it is only to be done if the dash warning is on for an oil change at the same time the vehicle hits its 6 month cycle.

Regardless, the highway driven 3.6s don’t leak nearly as early as the ones with low mileage and a million starts and stops per day. I did the oil cooler recently on the 100k mile one only because I was replacing its spark plugs, it was barely leaking. Radiators seem to be the same…they leak on the abused vehicles but not on the couple high mile ones we have.

I can’t make heads or tails of it. I think the frequent stop start ones are obviously driven hard, maybe the extreme temperatures on shut down are hard on the plastic parts used?

 

[nobb]

When people say maintenance, that really just means doing oil and other fluid changes on time. While that's important for mechanical parts, IMO, I don't think that has much effect on how well an RTV or oil seal will perform.

These elastomers break down with time, use, and temperature. While letting a vehicle sit is not good (the seals dry out), I also don't think running extreme long miles is good either due to the heat. Excessive thermal cycles from start/stopping is probably not good either.

I remember changing the timing belt on my 4Runner and the lower crankshaft seal was noticeably more brittle and hard vs the upper camshaft seals. They both have the same amount of mechanical use, but the lower one was obviously exposed to more heat.