Need leak turbo gasket and gas mileage advice

[MichaelU295]

I found a leak between the exhaust manifold and turbo. I put my finger there and felt the hot air escaping while the engine is running. It missed one stud/bold there. There is only 3 left instead of 4. Is it a show stopper and have to be addressed immediately?

In the other hand, my gas millage is only average about 7mpg during 7,500 miles. Is it normal or I have to look further into the engine condition.

I only have my RV for a year and it is 1997 HR Navigator with Cummins mechanical 8.3 325 hp.

Please advise.

Thanks.

[BFlinn181]

Your mileage isn't too bad for a diesel pusher, but without your RV details, it's hard to tell exactly. The leak at the exhaust and turbo could be robbing you of boost pressure and that would also mean with it fixed mileage might get a little better.

If you go to "User CP" tab you can "edit signature" and add info about your RV and anything else you'd like to share.

[MichaelU295]

I fixed the turbo gasket leak. The gas mileage seems to be better at 8mpg. Our members here with the similar engine/coach reported ~10mpg. I believe that bad gas mileage is a sign of some engine mechanical issue.

Where should I look further? My turbo boost only show max at 20psi, is it ok?

Thanks,
Michael

1997 HR Navigator, Cummins Mechanical 8.3 325 hp, Approx. 31,000 Lbs

[barmcd]

Originally Posted by MichaelU295

I fixed the turbo gasket leak. The gas mileage seems to be better at 8mpg. Our members here with the similar engine/coach reported ~10mpg. I believe that bad gas mileage is a sign of some engine mechanical issue.

Where should I look further? My turbo boost only show max at 20psi, is it ok?

Thanks,
Michael

1997 HR Navigator, Cummins Mechanical 8.3 325 hp, Approx. 31,000 Lbs

I've got a 2000 Dynasty with the 8.3 and average 7.5 mpg. I don't think there is any way you can get ten in a 31,000 lb coach.

[RightUR]

"If it moves, It wears out," you've heard that before right? You have a '97 so loss of Fuel efficiency is understandable. Over the years your motor will lose compression (cylinders). Then you have other moving parts that decrease efficiency like you crankshaft, valves, engine timing, oil circulation mechanism, and so on.
But hey there's light at the end of the tunnel: You can get some of that
"efficiency" back. Just start by replacing piston rings, valve guides and seats, bearings and bushings for starters.

[Ivylog]

20 boost is low...should be mid 20s for that vintage 8.3. Without knowing how fast you drive and how much you weigh, 8 may be excellent.

[udid]

Originally Posted by RightUR

"If it moves, It wears out," you've heard that before right? You have a '97 so loss of Fuel efficiency is understandable. Over the years your motor will lose compression (cylinders). Then you have other moving parts that decrease efficiency like you crankshaft, valves, engine timing, oil circulation mechanism, and so on.
But hey there's light at the end of the tunnel: You can get some of that
"efficiency" back. Just start by replacing piston rings, valve guides and seats, bearings and bushings for starters.

True....but preventative maintenance is the key. Keep up on the oil changes, tune-ups, coolant changes and the engine will live for many...many...many miles with few worries engine wise.

I just turned 251,XXX miles on my Toyota Highalander 2.4L and the engine hasn't missed a beat and will get 26mpg on the highway. My 1972 VW Westy hardtop has over 300,000 miles on it and I've rebuilt the engine twice in it going from 1.7L (stock) to 2.0 then finally 2.1L (2056cc T-4) PM is the key.

[RightUR]

Originally Posted by udidwht

True....but preventative maintenance is the key. Keep up on the oil changes, tune-ups, coolant changes and the engine will live for many...many...many miles with few worries engine wise.

I just turned 251,XXX miles on my Toyota Highalander 2.4L and the engine hasn't missed a beat and will get 26mpg on the highway. My 1972 VW Westy hardtop has over 300,000 miles on it and I've rebuilt the engine twice in it going from 1.7L (stock) to 2.0 then finally 2.1L (2056cc T-4) PM is the key.

good stuff. Preventive maintenance is the 1st step. But I'm quite sure a MH enigene works much harder than your 2.4 in a highlander, right? But your point is very valid.
As for your 1972 Vw, while it's your pride and joy, it's unfair to bring it up because if you rebuilt your motor 2x then you replaced all the wear and tear parts out with new ones, like I was saying previously. New cylinder rings, bushing and so on.

[NHRA225]

Wll ? I'll chime in here.
My 1992 American Eagle 6CTA8.3 all Mechanical has 225,000 on the clock and it runs great and I pull a 10,000 lb Race trailer all of the time.
I've had some issues along the way and also blew a Turbo gasket and limped home. I also have a TST Fuel plate Kit installed with a HP Rating of 450 HP. Not that I use it often but I have it and I can pass anything on the road if I need to. I drive the Speed limits and my Fuel mileage varies with the Travel variations-- Hills-- Flats ect You get it.
My last trip from Indy to Brainerd MN -- All Flats I got 10 mpg My next trip to Charlotte will be 8 mpg as there are more hills and Mountains to deal with . My point is you will never get the same mph all of the time .
Now- Maintenance!
Me ? I change Oil and Filter every 10,000 miles Rotella T4-- Fuel Filters every 6,000 miles - Diesel Fuel is dirty these days and I notice a difference when I change them.-- Air Cleaner - Every 6,000 also .
Allison MD3060 -- Filters and Delvac 1 -- every 50,000 miles.
These Older Cummins Engines were made to work hard, So if you only drive it a few times a year - you can expect issues from time to time.
Hope this long winded post helps you out !

[Ray,IN]

Originally Posted by RightUR

"If it moves, It wears out," you've heard that before right? You have a '97 so loss of Fuel efficiency is understandable. Over the years your motor will lose compression (cylinders). Then you have other moving parts that decrease efficiency like you crankshaft, valves, engine timing, oil circulation mechanism, and so on.
But hey there's light at the end of the tunnel: You can get some of that
"efficiency" back. Just start by replacing piston rings, valve guides and seats, bearings and bushings for starters.

At what mileage point would you recommend doing that for a diesel engine that normally runs 350,000 miles before an in-frame overhaul is scheduled?

[RightUR]

Originally Posted by Ray,IN

At what mileage point would you recommend doing that for a diesel engine that normally runs 350,000 miles before an in-frame overhaul is scheduled?

There a many factors to consider before overhauling an engine and Gas consumption (which in itself is influenced by another long list of factors for ex. Your driving habits: some have a lead foot, some press down on the gas gradually when taking off at a red light, some practically floor it, some like flying down the hwy between 65-75 mph, some drive 60-70 in the rain and so on)is at the bottom of the list. Some of your mechanics will say overhaul at 35000 Gallons (that's roughly 240K to 250K miles), but even that is subjective. So on your bigger engines your motor is supposed to eat 3/4 to 1 gallon of oil every 10K mile, now if it's eating a gallon every 1K miles, I'd be very concerned and have it checked out. Also you may want to ck your Compression and vacuum readings, that could also be an indication. But your truckers may get a overhaul every 600k to 850K miles, but that's because they use it everyday for hours. Many Class A owners, use the MH then Park it for weeks and months and that's not good for a motor. these things are meant to be Run. I start mine 2x a week for 30 min when it's not being used. You don't want there to be too much condensation build up in your motor either, so you want to run that bad boy.
Look If john is getting give or take 8 miles to the gallon and you are getting 7, I wouldn't sweat it. But if you do get an overhaul do the math first and figure out how many miles it will take before the $4-5K overhaul pays for itself.

[Ray,IN]

Originally Posted by RightUR

There a many factors to consider before overhauling an engine and Gas consumption (which in itself is influenced by another long list of factors for ex. Your driving habits: some have a lead foot, some press down on the gas gradually when taking off at a red light, some practically floor it, some like flying down the hwy between 65-75 mph, some drive 60-70 in the rain and so on)is at the bottom of the list. Some of your mechanics will say overhaul at 35000 Gallons (that's roughly 240K to 250K miles), but even that is subjective. So on your bigger engines your motor is supposed to eat 3/4 to 1 gallon of oil every 10K mile, now if it's eating a gallon every 1K miles, I'd be very concerned and have it checked out. Also you may want to ck your Compression and vacuum readings, that could also be an indication. But your truckers may get a overhaul every 600k to 850K miles, but that's because they use it everyday for hours. Many Class A owners, use the MH then Park it for weeks and months and that's not good for a motor. these things are meant to be Run. I start mine 2x a week for 30 min when it's not being used. You don't want there to be too much condensation build up in your motor either, so you want to run that bad boy.
Look If john is getting give or take 8 miles to the gallon and you are getting 7, I wouldn't sweat it. But if you do get an overhaul do the math first and figure out how many miles it will take before the $4-5K overhaul pays for itself.

There are numerous errors in what you state. Running diesel engine for 30 minutes will NOT bring operating temperature up to normal to evaporate condensation, especially at low idle, it must be driven for at least 2 hours to accomplish that. I suspect you are referring to a gasoline engine since that is to what you refer in your first sentence.
It would be a total waste of money to do an inframe overhaul of a medium/heavy duty diesel engine simply in an attempt to obtain 1-3 MPG. The money spent on that ($7-$12,000) would buy many hundred gallons of diesel fuel.

[RightUR]

Originally Posted by Ray,IN

There are numerous errors in what you state. Running diesel engine for 30 minutes will NOT bring operating temperature up to normal to evaporate condensation, especially at low idle, it must be driven for at least 2 hours to accomplish that. I suspect you are referring to a gasoline engine since that is to what you refer in your first sentence.
It would be a total waste of money to do an inframe overhaul of a medium/heavy duty diesel engine simply in an attempt to obtain 1-3 MPG. The money spent on that ($7-$12,000) would buy many hundred gallons of diesel fuel.

Uhm, again reading comprehension. I said I run my motor 2x week for 30 min. But not for condensation purposes. I do it just to keep everything functional as best I can, because like I said motors are meant to be run. And if you continue reading, I wrote as an example, if "John" is getting 8 miles to the gallon and the OP is getting 7 miles to the gallon, I'd think very hard about getting an overhaul, to me it wouldn't be worth it, but I don't know the OP, maybe he's a perfectionist and has money to spend. I don't know. So much for numerous errors, obviously counting is not your forte either.