OK. I've had a blowby issue since I got the truck.

I've been told it can be any of the following:
1) head gasket
2) turbo seals
3) rings
4) bad injector
5) bad exhaust valve guides


I ran a manometer test (home made variety) and got about 2.5 times the normal readings. The engine doesn't use oil, but it does have a LOT of blowby. When you stop at a light at night, it looks like someone is pouring oil on the exhaust manifold.

I just got the results of my lastest oil analysis yesterday. I called them today, and asked them some questions and below are their answers based on the analysis.

1) head gasket - none of the tests indicate any kind of leakage unless it is possible for it to leak compression without getting antifreeze in the oil
2) turbo seals - IF the turbo seals are letting pressure get by and into the crankcase, this could fail to show up in the analysis
3) rings - none of the tests indicate abnormal wear at all. Chromium was only 3 ppm, and iron was 55 ppm. The tech said if there were any wear issues (like bad rings), the numbers would have been a lot higher
4) bad injector - this may be an issue, but there is no fuel dilution (< 1% vol)
5) bad exhaust valve guides - again, none of the analysis seem to indicate any abnormal wear of the metal components in the engine.


The only abnormal things were high silicon and a slightly higher than normal viscosity. The high silicon may be from my sampling, or from antifoam agents, as it was kind windy that day, and some dirt/dust may have gotten in the sample. No signs of any air filter issues elsewhere.

Below are the results, if anyone sees anything that concerns them, please let me know. This was with 3200 miles on the oil, and 138k on the engine.

iron 55 ppm
chromium 3 ppm
lead 3 ppm
copper 2 ppm
aluminum 9 ppm
silicon 97 ppm
boron 38 ppm
sodium 10 ppm
magnesium 94 ppm
calcium 2480 ppm
phosphorous 1163 ppm
zinc 1358 ppm
molybdenum 7 ppm
tin, nickel, silver, barium, titanium, vanadium, potassium 0 ppm

fuel 1% vol
vis @ 100 C 20.44 (15w40 castrol, diesel rated)
water 0% vol
soot/solids 0.2% wt
glycol neg
tbn 5.7
f-soot 0.2

Their comments said excessive wear is not indicated, and said nothing else but to change the oil if not done at time of sample.


Any advice on what may be causing the blowby is begged for. After this, I amnot sure if the rings or head gasket or valve guides are the culprits.

 

The 1% fuel contamination is higher than I would expect unless you do a lot of stop and go driving, or do not adequately warm the engine before pulling a load. The same for the zinc and phosphorous levels, but the brand of oil you use contains a buffering compound that may be breaking down from combining with water from the combustion process, and that can result in those levels being up a bit and the calcium reading being where it is. If that happens the carriers used by the oil to suspend the long chain polymer molecules that give your oil its multiviscosity capability will start evaporating and creating excessive blow-by.

From the rest of your test results I would suspect your truck is pretty normal. What you may want to do is to make sure your thermostat is up to par and allowing the engine to adequately warm. Or, if you do a lot of stop and go driving in cool weather install a weatherfront to get that engine operating temperature on the high side of normal.

If you are having excessive oil consumption, which you do not indicate, I would pull the turbo and inspect it for excessive rotor shaft end and side play.

Otherwise, I would check my fuel mileage and make sure it is where it should be. If you fuel mileage is down, then check the transfer pump for a leaking internal seal on the pushrod side. That will allow diesel to contaminate the oil and create a great deal of blow-by, and would account for the 1% fuel contamination level. That seal does not have to leak very much to create all sorts of blow-by and the additive package in your oil will hide a lot of diesel contamination.

When I see these kind of test results and cannot find a mechanical fault, I usually recommend the owner switch to conventional Delo oil and change the oil and filter every 3,000 miles for a while and then do a test. Many times it turns out to be something as simple as stop and go driving and failing to let the engine run extended periods at normal operating temperatures.

 

It has done this with 3 different brands of oil (tried diff brands to see if it made a difference), and the lift pump is new, did it with the old one too.

I do a good bit of stop & go driving (work is only 3 miles away), and a good bit of 25 mile trips one way and back. The truck is not my daily driver, I drive it when I want to, and when I am towing.

It has been doing this thru the summer (I got it in august) and there was no real difference.

No loads, I only tow roughly once a month, and I let the engine get up to operating temp before I do (let it idle for 5-10 minutes). Tstat seems to be working fine, it gives the same wagging 145-190 reading as everyone else seems to get.

I did have a lot of oil consumption, then I fixed the leak. Since then, I haven't used any oil that can be noticed.

The oil was castrol 15w40, diesel rated, cummins approved

MPG is around 15-16, which from what I can gather, is about normal for a 12v with 4.10 gears.

My truck seems to be like every one elses's I have seen or rode in....except for the blowby. Frankly, it is embarassing sometimes.

 

I am going to assume your using a .221 blow-by orifice and getting more than 12 in. of blow-by at full load ? if you are , you can fabricate a drain for the turbo to drain with a Y to the engine and a gate valve on both sides to drain into a bucket also... run engine at full load and shut the drain to the engine and run it into the bucket and watch your manometer for change. it doesnt take long

 

Vacuum leak will also cause excessive blowby.

 

vacuum pump has been rebuilt, and seems to be working fine, as well as all accessories.

how can I check this ?


JohnCA58,

Will this test rig you describe be to see if the turbo seals are the culprit ??

I was thinking I could disconnect the turbo drainline, and put a funnel or something similar under the turbo, so the oil would still make it back into the crankcase, but I could see if the blowby was from the turbo, or if it dropped (the manometer reading) when doing this.

I used the manometer set up described on here, don't remember the hole size, but I have a nice 1/2" titanium pipe plug with it in it (ok, so it was a peice of scrap - and hard as heck to drill !!!).

 

yes it is to isolate the turbo as the cause of your blow-by , for checking blowby use the correct orifice .221 ,

 

I use a hand vacuum pump with gauge and hook it up to an unused tee on the firewall. It should pump down and hold vacuum for a very long time, even days, if there are no leaks. You might not have a leak with the vent controls or in 4wd in some positions vs others.
What happens with a vacuum leak is that the vacuum pump turns into a compressor with the exhaust venting into the crankcase thus pressurizing it.

 

Yes JohnCA58....I used a .221 orifice, and got 18"-21" of rise.

infidel, I will check again, but I think I disconnected the vacuum pump and capped it off, and it made no difference in the visible blowby at idle.

 

I just got done testing the vacuum system (in the cold rain no less). Seems to be fine. The vac pump will pull 25+ inches at idle, and the system (chassis side) only lost 1/4" of vacuum in an hr...went from 27 1/4" to 27". I also saw no noticeable change in the blowby with the pump connected or capped.


Now, I did look at my turbo, and it has me concerned. I have between 20 and 30 thou of side to side play (maybe more, I'm guessing here since my dial indicator wasn't long enough to get in there), but it doesn't hit the sides of the case that I can see.


The blowby is bad at idle, but it is the worst when you come down from higher rpm. It seems to be fairly constant, not really pulsing like it would if it was a single cylinder or two causing it.

 

Side to side play in the turbo is no big deal as long as it doesn't hit.
Start worrying if there is fore to aft play, there should be virtually none.

 

but wouldn't the side to side play allow the seal to leak ?

 

Not necessarily. The only times it wouldn't be centered is when you're pushing it unless one of the blades was chipped and turbo is out of balance, then you really notice a problem.