Long trip woes

[1968k10blue]

So, this past weekend, I took my truck ice fishing, and was about a 300 mile round trip. and basically in that time I used over a gallon of oil, what do you think would cause this? mostly freeway driving. I plan to go through the engine come summer time, but just curious what you guys think. I am thinking probably a combination on rings and valve seats. multiple plugs are definitely fouled out. SBC 350 from a 73 pickup, not really sure on miles/mods/previous work.

[steelhorse]

Sounds like a case of worn the hell out. I recommend a 383 stroker kit with a new set of aluminum heads.

[LockDoc]

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Wear in the engine plus a plugged or stuck PCV valve will do that.....

LockDoc

[Rich916]

Not an expert, but if plugs are fouling (from oil) then most likely rings are gone or going.

[Ridgeclimber]

I would start with a compression test on all cylinders with the throttle at w.o.t. If the compression is low, put some air in the cylinder and do a leak down test to determine where the loss of compression is going, out the exhaust, intake or base. If the compression is ok tune it up with new spark plugs, cap rotor. I always use 15w40 motor oil. If you are fowling plug and burning oil the thicker oil will help. I am a heavy duty mechanic and I have worked on commercial trucks with 1,250,000 km and the engine has never been apart. So if 15w40 motor oil can work like that I am sure it can keep my small block running. I use 15w40 in the lawn mower, wifes car, harley, dodge diesel, jet boat and never had a problem.

[MARKDTN]

Change the PCV valve first. You can use a lot of oil if it sticks. After that, do a compression test and cylinder leakdown test and see if there is anything obvious. Could put in new umbrella valve stem seals, but that would only last a bit if the guides are really bad.

What kind of oil are you using? I had a '96 Caprice that started using oil and fouling plugs at 60K. I had always used Castrol, but I switched to Valvoline and the problem went away. I put new plugs in at 60K and at 100K they still looked good. I am not saying Castrol is bad oil, it was just not compatible with the LT1 in that car for some reason.

[1968k10blue]

Okay, I will probably have to rent some tools come friday and check all that out, I have no idea what brand of oil was in it, but ive been putting cheap oriellys oil in it since i noticed it used it up, all 10w-30

[engineer_gregh]

With the engine running pull the PCV valve. If you have vacuum coming from the bottom of the valve good, if not replace. That was causing oil consumption with my 71 307 stock motor.

[1968k10blue]

would a bad pcv cause 2-1/2 quarts of oil to be burned in about an hour and a half at 3000 rpm the whole way?

[dan42]

...uh - 3000 rpm the whole way? You're gonna burn oil; maybe not that much, but that's pushing a well worn 350.

[engineer_gregh]

I bought my truck out of town and had to drive it about 3 hours. It burnt about 2 quarts of oil. The PCV valve also caused a bit of a rough idle, much like the stock engine had an RV style cam. Once I changed the valve the idle smoothed out but I've not had it on another road trip to check the oil consumption. I honestly believe mine was the original PCV, it had the GM part number and was completely clogged. Its $3-$4 dollars, just change it.

[Custom 68]

Originally Posted by 1968k10blue

would a bad pcv cause 2-1/2 quarts of oil to be burned in about an hour and a half at 3000 rpm the whole way?

Humm, 150 miles in 1 1/2 hours...
lol that would be 100 mph. But it does sound like it is just pretty tired and ready for a refresh.

[1968k10blue]

well it was actually 100 mile via freeway, but i did a decent bit of in town driving that weekend. maybe i can talk my dad into selling me into selling me his rebuilt 455 olds big block thats sitting on an engine stand in my garage

[1968k10blue]

And the wired part is , is that I made a trip half that ling before and didn't burn any oil, driving the same way only difference was distance and it wasn't winter

[bigmac73]

after using that much oil, are you blowing smoke out the back or does the tail gate has a oily film on it from exhaust residue,

[1968k10blue]

No, and that was another thing that confused me, the exhaust was actually the most clear I had seen it, but I also had it sitting in fresh snow at idle for about 2 hours and there was no oil on the ground. And also the engine runs great, but I'm not sure what is supposed to feel tired, because the only other vehicle I have driven consistently has a low mileage v6, so I have nothing to compare to

[67ChevyRedneck]

How much were you looking to spend on your rebuild? This can be done in a weekend with a warranty, as opposed to machine shop time, clean up and rebuild time... etc...

http://67-72chevytrucks.com/vboard/s...=606983&page=8

http://www.ebay.com/bhp/gm-350-engine

[1968k10blue]

I have thought about that too, but honestly, I Wang to go into mechanics as a career, so if I bought a new one I would probably still go through the old one

[1968k10blue]

Well, it's not my pcv valve
Oh and at a closer look I do have oil residue on both sides of the truck where my exhaust exits, looks like I'm going to save up a pretty penny here soon