This truck leaks a lot. The mechanic says most of it is blow-by. Do certain driving habits cause increases in blow-by?

Example... lugging the engine a little too long before an upshift

Or, is it more likely the thing needs rings? It has 90K miles on it.

 

It should not be rings, the thing is barely broke in. If the blowby is that bad, there must be a major problem. Make sure the vent tube is open.

 

Blow by is internal crankcase pressure. What I've done is get a oil filler off a FL 80 and install it on your engine on the front case. That will give you 2 oil vents and really help with the internal pressures. Almost stopped my blow by at 331,000 miles. My engine breaths a lot better now.

..Preston..

 

Any pictures or part numbers to go along with that BOMB Preston??

I need to do something about mine, as well.

Thanks,
Chris

 

Sorry, don't have a number at the present time but will try as soon as possible to get it for ya.

..Preston..

 

His commercial engine should have the side breather on the side cover. He can just add the Dodge breather to the front cover. I ran one for a while. But the engine should not have that much blowby. If you do, get ready for everybody to tellyou that there is a broken part handing fromt he engine.

 

Not sure if you even have a vacuum pump on your setup but a vacuum leak will increase blowby quite a bit. The way the vacuum pump works is that it exhausts air into the oil sump, if there are no leaks, no exhaust into the crankcase. If there is a vacuum leak the pump is working all the time much like an air compressor, pressurizing the crankcase.

 

Ok guys.

I have a good bit of blowby...some times.

It seems to do it whenever it wants, but it is not even noticeable if pulling a load. Mainly when driving unloaded.

I mean, I can pull up to a stop light, and it looks like I have a massive oil leak onto the exhaust. other times, it can't be seen at all.

I fully expected it to get worse when towing, but it is actually less.

Any ideas ?? I'm beginning to really think it is some kind of intermittent vacuum pump leak.

It's really annoying to pull up next to a chebby or furd and let them see all the smoke it belches out sometimes. (not the fun black kind or smoke either)

 

no new ideas ?

 

There is not much to go on. You more or less have the following choices.

Head gasket
Vacuum pump
rings
stopped up breather

Check the blowby and see if it is high. Then look for the leaks. I would not pull anything apart for blow by unless you can determine that it is high.

 

don't thin it is head gasket..no other signs of failure there.

vacuum pump....quite possibly.....

rings....maybe, but if that was it, I'd think it wouldbe worse under load

stopped up breather....what breather ?? I think mine only has a tube off the side of the block. I haven't seen any thing that looks like a breather on it anywhere for the crankcase.

I've only had this truck since the end of july.....still trying to learn

 

I put a pressure gage on my blowby tube, and it rose to about 3.5 psi before it pushed the dipstick tube out enough to relieve that way. It only took about 30 sec or less to rise that much.

Is this terminal ??

 

All you were measuring is how much pressure it took to blow the dipstick out. If the the dipstick was well secured the pressure would have kept climbing until an engine gasket blew out.
Here is the correct way to do it.

You need a blowby tool. a blowby orifice tool is simply a tee with one .221" (15/64-in) outlet. Connect one end of the tee to the end of the blowby tube. Put a manometer on last tee outlet. That is your blowby tool. They sell them at the Cummins, but I have made my own plenty of times. A simple manometer can be made by looping into a U 6' of clear tubing with water in it half way. Measure how high the water level rises with a tape measure, multiply it by 2, convert it to LPMs

Rough conversion is 1"= 27 lpm, add 3 lpm for each one inch (1/2'' of rise in the tube) of water

New engines numbers are;
63 liters per minute(2.5" water rise = 5" of water) @ 2200rpm,
76 L/Min (3.5" rise) @ 2500rpm
85 L/Min (4.5" rise) @ 2800rpm.

Worn engine that needs rebuilding are roughly double i.e.
126 L/Min(10.5"rise) @ 2200rpm
152 L/Min(14.5"rise) @ 2500rpm
170 L/Min(17"rise) @ 2800 rpm

The valves could also be out of adjustment.

Another way, same idea, is to block the blowby tube with a 1/2'' pipe nipple with a cap that has a 15/64 hole drilled in it. Use 3/8'' id looped clear tubing with water in it slipped over the oil dipstick tube. Use sharp tipped felt marker to mark the water level with the engine off, have someone start an already warmed up engine and run the rpms up to 2.2, 2.5 & 2.8k rpms. Mark each water level with the pen, measure then multiply each by 2.

This is all very simple to do, just hard to explain with words.

 

I have had the same problem. I run the truck for 8-12hrs. at a time. If you are pushing the dipstick tube out get a head gasket. They are pretty simple to do lots of room. make sure if you do the head gasket all your surfaces are flat. I really think these things don't like the gearing they have cause I have the same gearing as you. I picked up a new head and I'm gona O-ring the head and put a .010 over head gasket on it

 

Well, the dipstick tube isn't hard to move. not much of a seal there.

You're saying that even with the blow off tube plugged it shouldn't blow the dipstick out ?? (the only time it has ever blown the dipstick out is when the blow off tube was completely plugged with the pressure gage fitting)

There are no other signs of a head gasket problem (or at least not any signs I am aware of).

Infidel, I saw that and have it printed out previously....I figured the pressure reading would be as good.

Maybe I'll try the dipstick tube method this weekend.

I just find it hard to believe the head gasket is bad. better than rings I suppose tho.

the valves have been adjusted within the last 500 miles. the vacuum pump was just rebuilt and put back on tonight...still seems to be doing it. Hopefully, I fixed one of my oil leaks tho.