Did I ruin my engine?

[dpilot83]

I have a natural gas powered 4.3L Chevy engine serving as a power unit for an irrigation well.

It is equipped with a sight gauge for checking oil level while the engine is still running. If we change the oil and fill the engine to the full mark on the dipstick the oil wil become foamy and make checking the oil level with the sight gauge impossible. As a result we intentionally run the oil level lower than the dipstick says is OK. We have probably put ~10,000 on this engine using this method over the last 6 or 7 years since we installed it new.

It uses very little oil. Occasionally we overfill it and it makes the sight tube harder to read every time because some of the foam residue stays in the sight tube. Since it's tough to see and doesn't use much if any oil (I thought) we don't try very hard to check the oil level between oil changes (once every 168 hours before this year, this year I decided to switch to 336 hour intervals).

The engine shut down today at about 272 hours since the last oil change. As an looked it over I noticed that the oil level was VERY low, lower than I have ever seen it by far. I put some more oil in and tried to fire it up. It would not start. It has spark. I assume it has fuel and air although I'm not an expert at checking fuel on a natural gas engine.

The engine is equipped with a Murphy switch which is supposed to shut the engine down anytime the oil pressure gets low or the engine temp gets high so I would think even if it ran out of oil it would not do catestrophic damage but it would not start and it was exceptionally low on oil which seems pretty coincidental.

Tomorrow morning I guess I will go verify fuel and air and then check compression and timing.

Let's assume the Murphy switch worked correctly. Is it possible low oil levels that were still allowing for the oil pump to pick oil up to maintain oil pressure could cause me to ruin my compression rings? I tend to believe if I have compression I'm not in bad shape and I'll surely be able to get it running but perhaps there may be some other oil related problem I'm not thinking of?

Any thoughts on other things I should check tomorrow? I appreciate it, thanks.

 

[AVB]

I would lean toward a fuel problem. I don't think low oil would kill a 4.3 unless it was nearly dry. Especially if it is turning over fine. I used to work on a fleet of CNG forklifts and other CNG equipment. We had problems with fuel system components gumming up. A set of spark plugs wouldn't hurt either if they haven't been changed in a while.

 

[Johnny2Bad]

It sounds like you are likely to do more damage from your habit of overfilling the motor rather than underfilling. You should be able to run 2 quarts low (assuming it takes 4~5 quarts from empty) without engine damage of any kind. In your case (a stationary motor) it is even less likely that being a few quarts down with still some oil in the sump is a cause for engine damage, as the risk that cornering forces in a road-going vehicle that could uncover the oil pickup doesn't exist.

Maybe a teardown will reveal the real issue, maybe it just needs some attention as running continuously is definitely severe service.

272 hours [ 60x272 = 16,320 miles equivalent light duty (highway) and 30x272 = 8,160 equivalent miles severe duty (city or farm) ] is a fairly long Oil Change Interval (OCI) as it is ... how many hours have you been running the motor before you normally do an Oil Change?

On 4-stroke high horsepower boat motors (75HP+) the OCI is 100 hours.

Maybe I misunderstand your practices, but if I do understand them, you are running these motors VERY hard.

 

[dpilot83]

There are several things that you have to take into account when you consider how hard or a life the engines have.

The first and most significant is that they are running at a constant engine load all day long, never the slightest variation. That load is also a relatively light load. They are perhaps runnning at 40 to 50% of the power levels that they could produce? No load variations and low horsepower requirements relative to potential makes this a very easy job for these engines.

Secondly, natural gas burns quite clean which helps with longevity as well.

Anyway, they run about 1800 hours a year. This particular field actually has two engines driving irrigation wells for it. I came back to the farm in 2007 and the other engine on this field was there when it came back. At that time no one knew how old the other engine was. It looked like it was on it's last legs. Burned some oil, leaked some oil, ran rough sometimes, etc. that was 7.5 seasons of 1,800 hours a year ago and it's still running and in about the same condition it was then. I think maybe we did a little bit of head work on it about five years ago but nothing major.

I guess my point is that unless a mistake is made (like this) irrigation wells are generally expected to run 20,000 to 30,000 hours on cheap engines like these. In some other areas of the country where they run more expensive severe duty engines and run their wells more hours per year, I think they have higher expectations than that.

 

[dpilot83]

I do not have a habit of overfilling the engine. Like I said, we have marked a range on the sight gauge that keeps the engine from roaming the oil that is a significantly lower level than what the dipstick recommends.

I do have employees though. They seem to struggle with not overfilling it when they change oil.

In this instance an employee did change the oil last. I am wondering if I over emphasized not overfilling and between that and the sight gauge being difficult to read perhaps he did not fill it enough.

Regardless the responsibility falls on my shoulders. I should have replaced the sight gauge long ago. I also should have used extra care when checking the engine the last few days to make sure the sight gauge was reading correctly since I was running longer hours than I previously had run.

I switche to a 2 week interval instead of a 1 week interval because successful farmers around me run a two week interval. BITOG is probably a bad place to admit that. I do not pull samples on these which is likely how I should have made the decision.

 

[dpilot83]

I suppose my answer to the OCI was kinda in the last post but I forgot to address it directly. Every year before this year my OCI has been 1 week (168 hours). This year I switched to 2 weeks (336 hours) because that's what most farmers around here do and I wanted more margin in my life. Was not based on anything scientific such as oil samples.

 

[dpilot83]

One last note. Probably the biggest advantage these engines have for longevity is that they very rarely shut down and restart. Starting an engine is probably one of the hardest times for them as they transition from cold to hot and not lubricated to lubricated. These engines only go through that cycle once per oil change unless something out of the ordinary happens.

 

[NStuart]

Let me put my flame suit on, sounds like a great candidate for an oil bypass setup

 

[Linctex]

You did not hurt your engine.

300 Hour intervals are probably too often on an irrigation engine running natural gas. I'd run 500, but check level often. I'd use 15W-40 HDEO.

Most engines are good for getting "the last drop" of oil sucked up - I have personally seen vehicles that got an oil light or dropped pressure, and when the plug was pulled, less than 1/2 quart ran out!!!

I know of a little Kubota D905 running a Marathon 6.5Kw generator head that runs 24/7/365... it nearly never gets it's oil changed (usually once or twice a year), just added. It has about 50,000 hours on it now, and most of those on 4,000 hour oil changes.

 

[dpilot83]

Originally Posted By: NStuart
Let me put my flame suit on, sounds like a great candidate for an oil bypass setup


Why, when running without will take me to 20 or 30 thousand hours without even opening the engine up most likely?

 

[CT8]

Originally Posted By: NStuart
Let me put my flame suit on, sounds like a great candidate for an oil bypass setup
With a good air filter there in not enough to filter out once the engine is broke in. A bypass will not stop the oxidation of the oil.

 

[dpilot83]

Originally Posted By: Linctex
You did not hurt your engine.

300 Hour intervals are probably too often on an irrigation engine running natural gas. I'd run 500, but check level often. I'd use 15W-40 HDEO.

Most engines are good for getting "the last drop" of oil sucked up - I have personally seen vehicles that got an oil light or dropped pressure, and when the plug was pulled, less than 1/2 quart ran out!!!

I know of a little Kubota D905 running a Marathon 6.5Kw generator head that runs 24/7/365... it nearly never gets it's oil changed (usually once or twice a year), just added. It has about 50,000 hours on it now, and most of those on 4,000 hour oil changes.


Thanks. We run John Deere 15W40 in these and have done so as long as I can remember. We do so because we have it in bulk (buy 250 gal at a time). Maybe not the cheapest but probably not the most expensive either and it has worked so far.

 

[The_Eric]

What does the Murphy switch control or shut off? Fuel supply or spark? Does the switch need to be reset? Is there a bypass/override button on it?

 

[dpilot83]

Originally Posted By: The_Eric
What does the Murphy switch control or shut off? Fuel supply or spark? Does the switch need to be reset? Is there a bypass/override button on it?


Murphy switch kills the spark. There is an override button that allows you to start it. As soon as you build oil pressure the override button can be released.

The gauges can be manually tested by shorting the gauge out with a screwdriver or something. If the engine dies, they are still working. I have not done that in awhile. If I get it running (almost to the field with tools now) I will test the gauges first thing.

 

[zorobabel]

Why not run a SAE30 or SAE40?
I fail to see the purpose of a multigrade oil in this situation. Use the amount of oil reccomended for the engine.

 

[dpilot83]

Originally Posted By: zorobabel
Why not run a SAE30 or SAE40?
I fail to see the purpose of a multigrade oil in this situation. Use the amount of oil reccomended for the engine.


Why not use what we have an abundant supply of and has historically proven itself to be an oil that allows the engine to last a long time?

Where might I find the specifications for how much oil I should put in a GM 4.3L with an industrial oil pan and an improperly marked dipstick?

We filled it according to what was written in white paint pen on the engine when we bought it new (4.5 quarts). It also had white paint pen marks on the sight tube that corresponded. Also corresponded to the dipstick. But foaming your oil up because the crankshaft is in the oil is not good for things so we run less to keep the oil from foaming up.

It's worked fine for about 9,000 hours so I can't imagine it's too bad.

All of the cylinders on the starter side of the engine had about 170# of compression. All of the cylinders on the non-starter side had about 155 for some reason. Still way more than adequate on both sides and not obscene variation.

The diaphragm that controls fuel flow on natural gas and propane engines was damaged. On my way through get a new one now.

 

[dpilot83]

Uhhhg.

In my original post I said "it has spark".

I did not have my spark tester with me so I tested that by taking some electric fence wire and bending it so it would securely insert into the spark plug wire. Then I balanced the spark plug wire so that the electric fence wire was something like 1/4" from a ground. I cranked the engine and saw what I thought was a great spark.

Two issues. Perhaps it was less than 1/4"? And it was dark so the spark I saw likely looked way better than it was.

So today I did a lot of stuff based upon the assumption that I had good spark.

After much failure and wasted time/money I decided to test spark again with my spark tester. Had no spark. Tested out of the coil wire and had good spark. Replaced cap/rotor and away it went.

Surprised that was the issue as my Dad replaced th cap/rotor for me about a month ago but whatever, it's running.

Thanks for the help everyone. Sorry it was a wild goose chase due to incorrect info in the original post.