Excessive blow-by and oil consumption

[Zoltan]

I am still under 3000 miles but I've already replaced 3 quarts of oil. There's no noticable oil leak under the hood and no smoke coming from the tail pipe. However I do get plumes of vaporized oil coming from the draft tube. It's very noticeable at lower speed and at stop lights (it's like someone is blowing cigarette smoke in your face).

I have adjusted the valve lash and I get around 35 mpg. I am thinking that the valve stem seals need to be replaced. Any other ideas?

[philip]

I am still under 3000 miles but I've already replaced 3 quarts of oil. There's no noticable oil leak under the hood and no smoke coming from the tail pipe. However I do get plumes of vaporized oil coming from the draft tube. It's very noticeable at lower speed and at stop lights (it's like someone is blowing cigarette smoke in your face).

I have adjusted the valve lash and I get around 35 mpg. I am thinking that the valve stem seals need to be replaced. Any other ideas?

Valve stem seal replacement MIGHT improve your oil consumption IF the present ones have significantly deteriorated. But stem seals will not have any effect on road draft tube emissions.

Blow-by exiting the road draft tube is NORMAL as are drips on your driveway from the tube. Having said that, plumes of smoke rolling out from under the fender and/or out in front of the headlamps while stopped at a traffic light is excessive. Blow-by CAN be due to one or more of the following:

1) worn compression rings and/or scored cylinder walls,
2) a moderately overheated engine,
3) old engine oil that has lost alot of its TBN,
4) oil that is highly contaminated,
5) a cylinder that is misfiring or firing early,
6) injection timing that is too far advanced for the fuel used.

I know you pull a sustained grade in 3rd gear. This situation probably aggravates the blow-by plume until the engine cools off a bit. I'd say this is normal.

In trying a couple of different non synthetic motor oils (Rotella, Mobil Delvac, Chevron Delo, and NAPA), I discovered NAPA's house brand oil (Valvoline) netted the least amount of visible blow-by after a long haul grade and the best oil consumption by a considerable distance. On NAPA 15w-40, my engine passes 1 qt in about 3500 miles.

[Zoltan]

Hello Philip,

I've been using Valvoline Premium Blue 15W-40 Diesel engine oil. I got a deal on it ($8/gal) a while back at Checkers. I picked this oil after reading your note on the Napa oil.

1) worn compression rings and/or scored cylinder walls,
2) a moderately overheated engine,
3) old engine oil that has lost alot of its TBN,
4) oil that is highly contaminated.
5) a cylinder that is misfiring or firing early.
6) injection timing that is too far advanced for the fuel used.

I can exclude 3 and 4, but not the rest. I am waiting for the compression tester to arrive so I will go down the list. The operating temp I get is between 1/3 and 2/3 of the Normal zone. It's 2/3 uphill 1/3 downhill, 1/2 instop and go traffic.

Does this sound normal to you? Outside temp is seldom higher than 92.

[philip]

SNIP. The operating temp I get is between 1/3 and 2/3 of the Normal zone. It's 2/3 uphill 1/3 downhill, 1/2 instop and go traffic.

Does this sound normal to you? Outside temp is seldom higher than 92.

Coolant temperature should not fluctuate THAT much with varying engine loads if the thermostat and radiator have plenty of reserve capacity to dump heat. Take a look at this recent picture. Note the ambient and coolant temperatures. This was traveiling along at 60-65 mph on level ground with A/C running on a 105 degree day.

At first blush, I would guess your thermostat is not regulating correctly and secondarily either air flow through or coolant flow through the radiator core is impaired.

Hot engine coolant will raise oil temperature via the oil heat exchanger. Higher temperatures exacerbate blow-by.

[asavage]

2. . . . the engine is still running hot (it's steady in the middle).

That's where it's supposed to be.

[zen]

To help with oil lose, one can do a few mods.

These won't cure the reason why its happening. You still will have to go there but...

Either have an oil seperator ... (moderator: SNIP)

[asavage]

Zoltan didn't say he is getting liquid from the draft tube, so mods wouldn't affect oil consumption. The later SDs routed blow-by gases to the air intake, just like modern engines Philip did a very good writeup (with pictures for those of us who need 'em!) in this post.