How to fix Blowby

[devilphrog]

I've read on this forum that you can re-anneal the copper sealing rings for the injectors by removing them, heating them red hot with a torch, and letting them slowly cool down on their own; it allows the copper to get "soft" again for reuse if you don't have a set of replacement sealing rings.

 

[Chainbreaker]

If blowby due to broken rings, excessive wear, cracked piston or what have you... its usually going to result in a consistent positive pressure that is readily noticeable with dip stick removed (which sounds like what he is describing).

Also, a close watch of cold oil level should be monitored as an indicator that something is amiss if it slowly lowers bit-by-bit after running an hour or so between runs. I always check my units when stone cold the next day (after being run the day before) when oil has had time to completely return to crankcase.

 

[Triple Jim]

If I pull out the dipstick on my 003A while it's running it will do more than put a mist on my hand, it'll spray oil all over the place. I imagine a 2-cylinder engine would do even more. Are you sure it's not something like previous times were with cold, thick oil and you recently tried it with the engine hot, for example?

 

[NormB]

I've read on this forum that you can re-anneal the copper sealing rings for the injectors by removing them, heating them red hot with a torch, and letting them slowly cool down on their own; it allows the copper to get "soft" again for reuse if you don't have a set of replacement sealing rings.

Not even sure you'd need to get them "red hot."

I once owned a 1975 Norton 850 Commando. Brits used a solid copper head gasket. Local shop annealed this when replacing a worn out valve lifter. A year later I put in a set of Silicon-bronze valve guides, lapped the valves, and annealed the gasket in a toaster oven.

Don't recall exact temp but I anneal rifle cases (.223, .308, .300win mag, .375 H&H) with a propane torch and it only takes a few seconds each (I used TempaLAC paint to figure it out for each size years ago).

But yeah, should work with the injector seals, too.

 

[Guyfang]

If I pull out the dipstick on my 003A while it's running it will do more than put a mist on my hand, it'll spray oil all over the place. I imagine a 2-cylinder engine would do even more. Are you sure it's not something like previous times were with cold, thick oil and you recently tried it with the engine hot, for example?

Apples and oranges. A 003A has a positive pressure on its crankcase. The TQG engines not.


TM 9-2815-252-24, PDF reader page # 34
[FONT=&quot]3-5. CRANKCASE VACUUM,[/FONT]
[FONT=&quot]3-5.1. General. The value depends to some extent on the type and size of air cleaner installed on the engine. Regardless of type air cleaner used, vacuum with a clean air cleaner must not be less than a minimum of 0.79 in. (20 mm) water gage (WG). The vacuum is measured with a manometer at the lubricating oil dipstick hole with the engine running. In engines in good condition vacuum increases slightly with engine speed but not proportionally. A fluctuating vacuum may indicate faulty oil seals, valves, or piston blow-by troubles. Crankcase pressure can cause serious oil leaks and often occurs in engines which need overhauling

TEST first. Then decide what is the problem. But if oil comes out of your dip stick hole, you need to test.
[/FONT]

 

[fa35jsf]

Well I’ll check the oil level this evening since it will be cold and then test crankcase pressure if I’m able to.

Not having a TM in front of me, has anyone overhauled one of these engines? Guyfung? I’d imagine on a little two cylinder simple diesel it can’t be too hard to do. My concern would be finding parts and new seals. Any good places to pick those up in a cost effective manner? Possible cross referenced part numbers?


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[frank8003]

You work + think to freakin hard sometimes
un that thin loaded up and enjoy

We here are tryin to saved stuff like forever
but what the heck for .................................

Use what you got, when you need it
We all jealouse out here at 7 feet above sea level

work work and you get wha YOU NEED

 

[royalflush55]

You might try running some sea foam fuel additive thru the fuel tank also. If an injector is not working properly you could have a cold cylinder too. You can do this while it's running.

 

[fa35jsf]

Apples and oranges. A 003A has a positive pressure on its crankcase. The TQG engines not.


TM 9-2815-252-24, PDF reader page # 34
[FONT=&quot]3-5. CRANKCASE VACUUM,[/FONT]
[FONT=&quot]3-5.1. General. The value depends to some extent on the type and size of air cleaner installed on the engine. Regardless of type air cleaner used, vacuum with a clean air cleaner must not be less than a minimum of 0.79 in. (20 mm) water gage (WG). The vacuum is measured with a manometer at the lubricating oil dipstick hole with the engine running. In engines in good condition vacuum increases slightly with engine speed but not proportionally. A fluctuating vacuum may indicate faulty oil seals, valves, or piston blow-by troubles. Crankcase pressure can cause serious oil leaks and often occurs in engines which need overhauling

TEST first. Then decide what is the problem. But if oil comes out of your dip stick hole, you need to test.
[/FONT]

I have 1” of positive pressure.

So let me ask Guyfang, and please don’t think I’m questioning you; I know you’re an expert around these machines but I’m trying to understand.

I always believed crankcases would have some positive pressure. Slight but some. With pistons flying around and oil expanding it only makes sense to me. So how does this machine end up with a vacuum? What mechanism allows for that?

I guess I just don’t understand.


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[fa35jsf]

You work + think to freakin hard sometimes
un that thin loaded up and enjoy

We here are tryin to saved stuff like forever
but what the heck for .................................

Use what you got, when you need it
We all jealouse out here at 7 feet above sea level

work work and you get wha YOU NEED

Well I can appreciate that train of thought and if I had to rely upon this generator for my primary source then I absolutely wouldn’t be spending the time on this. But this is generator is a backup for me for winter storms or tornadoes. Therefor I can afford to take it offline in the off season for a few weeks to work on it.

I guess my way of thinking is if the piston rings are locked up or I’ve got a cracked cylinder then I could be causing more damage, and I definitely don’t want to do that.

I can understand people who have to accept a machine with some flaw because they NEED the power, but that doesn’t mean I need to abuse my machine.


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[Daybreak]

Howdy,
OK, let's get down to brass tacks.

OK a MEP-802A
what year?
does it have a rebuild tag?
How many hours?
How long have you owned it?
How many hours have you put on it?

Start simple, The Lister-Petter LPW engine design is old school. It's been around along time.
The MEP-802A likes to be loaded between 50-100% A lot of light loading will build up on the pistons, walls, injectors, and really bad fill up the exhaust with black goo. (Wet stacking)

A good hard load running for hours will probably help here.

No need to overhaul the engine just yet.

MEP-802A engine - Onan DN2M-1 is Licensed by ONAN to build it. It is a Lister-Petter LPW2. That being said, you take all the same parts, and add 2 more cylinders, its a DN4M-1, and/or LPW4.

Same valves, pistons, rings, valve covers, injectors, etc...

 

[fa35jsf]

Built in 2000. Tier 2 reset in 2010 for what looks like the lister petter engine. I’ve put about 10-15 hours on it in the last 1.5-2 years that I’ve had it. Sorry I don’t remember how many hours are on it total. I want to say around 500 +/-100.

And although I rarely run it hard, I also rarely run it at all. It doesn’t show any signs of wet stacking. The exhaust is dry

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[Chainbreaker]

I have 1” of positive pressure. So how does this machine end up with a vacuum? What mechanism allows for that?

I guess I just don’t understand.

Your answer is embedded within post #15 above. In a nutshell, its designed to scavenge vapors under vacuum via pathways to the intake. The vents within the valve cover he describes in that post are plumbed/vented intake tubes which by nature are under negative pressure when running.

 

[Tinstar]

Use it or lose it.

Sounds like a classic case of too little/too light of use.
Like already mentioned, I would run it at high load for hours before even thinking about a rebuild.
Seafoam in the fuel will help.
Sure these machines can sit idle for extended periods, but they don’t like to.
Running it weekly or biweekly or monthly keeps the seals happy and the moisture at a minimum.
You want it to start/work when needed.




I run my Kohler generator weekly+- to keep the engine and battery’s happy.
It runs for a minimum of one hour each time I start it, loaded as much as possible.
Fuel tank is always topped off afterwards to keep moisture down in fuel tank.
Seafoam always added to fuel.
It works for me.

I had it ready to go for the big storm we just had.
Luckily I didn’t need it.

More storms later this week.
Generators Ready.

 

[Guyfang]

Your answer is embedded within post #15 above. In a nutshell, its designed to scavenge vapors under vacuum via pathways to the intake. The vents within the valve cover he describes in that post are plumbed/vented intake tubes which by nature are under negative pressure when running.

Exactly.


Now, I will tell a little story. I think I wrote this someplace else, but no matter.


The first time I ran into this problem with an 803A, I called an old buddy in Communications and Electronic Command, (CECOM) for a hint. This was back in 04, I think. It was CECOM's policy, to first do the Vacuum test, then to dump the oil and filter, (I would save the oil in a glass jug and cut the filter open to take a look see at is in it). Next step was a new filter, and fill up the crank case with ATF. Run the set for 20 Min. Dump the ATF and filter, (once again, because I always have this urge to know, save the ATF and filter for inspection). New filter, cheap oil. Run it at 100% load for an hour or two. Dump oil and filter. New filter and good oil. Vacuum test. Improvement? Or not? If not, ATF in the jugs, left a day or two. Roll the engine over, WITHOUT injectors. Do feel free to place wads of rags over the injector holes before rolling it over. Or you will maybe have to take more then your monthly bath. Then reassemble. Test vacuum. Improvement? Or not. When its or not, replace engine. The Military doesn't do much engine rebuild. They simply don't have the time or tech experience. And down range, non of this would have been done. Simply engine replacement. No time to fool around, when folks are trying to send you home in a box.

And no, I am not an expert. Just an old mechanic who worked a bunch on this stuff. Its your right to question me. Keeps me honest.

Do some testing and poking around before you start thinking about rebuilding.

 

[Bmxenbrett]

You can open the oil fill on any engine and have oil mist coming out when running. Taking out the 4in long dip stick and having oil mist come out is totaly normal. By pulling the dip stick tube you would be removing any vacuum.

Removing a part and expecting the engine to run per spec is not going to happen.

 

[devilphrog]

I recommend you do what Guyfang talked about; but if you aren't running the unit often, and when you do you aren't loading it down you will be prone to wet-stacking the unit. You may want to consider coming up with a load test device in your off-season time (i made one out of sheet metal and dryer elements attached to a breaker panel and added a plug for this sole purpose, and wired the unit up accordingly) and run the unit from 50-100% capacity. Remember, these are old design diesel engines and they need heat to run cleanly. Adequate exhaust temperatures is created by a decent electrical load on the generator head

My hip pocket reminder for exercising my generator is to run it whenever I am cutting my grass. I've got a few acres of grass to cut and trim, so it gives me a few hours of run time every couple of weeks. No fancy calendar reminder or anything of the sort, just fire it up and put a variable load on the unit as I make passes around my house as I mow, and then work on a shutdown procedure as I'm doing final cleanup with my leaf blower. It's not any sort of scientific method or anything but seems to work, and also has some noise and diesel exhaust fume discipline built in as part of my routine to be a considerate neighbor and clustering all of my noise and smell making.

If you do end up needing to bust into the engine, if it's just a cracked ring or piston, it's not that bad of a process to pull the head, pop the pistons out, hone the cylinders, clean up and reassemble with serviceable components. You will only need to pull the generator top cover, and engine block crankcase side panel to get internal engine access. My cylinder walls weren't torn up and cleaned up easily, but your mileage may vary. LPW parts are available all over ebay, and can be cross referenced to the Onan part numbers and back to LPW part numbers. Replacement piston, ring, and wrist pin assemblies are about $75 each on ebay. Don't forget that you'll need a gasket kit. If you did have a seized piston in the cylinder wall, there is a strong probability that you'll need pushrods as well at a cost of around $15 each. All in, if you're adament on tearing into the engine and the walls are OK, you're looking at around $300 in parts + your time to replace.

 

[fa35jsf]

Thank you so much for all the replies to this thread. I know I don’t run it often enough or hard enough. Being in the military and being gone so often has prevented me from really working the machine like it needs. As posted in another thread I accidentally gummed up the fuel tank by leaving unstabilized fuel in it for 6-9 months. Whoops. Still have to fix that problem.

The procedure with changing the oil three times and using atf with flipping the engine over seems like a ton of work. I think I’d rather overhaul it if it came down to that.

Here’s my plan of action:

1) Build a break out electrical box that I can plug into the generator and have something to load test it. All I have now is the house which doesn’t work too well.

2) Change the oil and filter. I guess a basic diesel rated 10w-40 should be fine.

3) load test the gen as close to 100% for a full tank of fuel. ~10 hrs. My fuel is already treated with PRI-D (fuel stabilizer), Lucas Fuel Treatment (fuel lubricant and injector cleaner), and a Biocide to prevent fungal/algae. I guess I could also use some seafoam, although I worry about interactions with the other products.

4) then retest crankcase compression.

5) if still bad, try MMO in each cylinder and let that sit a few days.

6) repeat steps 3 and 4.

7) if still bad, overhaul engine as time permits.


I know there are probably several ways to skin the cat so to speak here, but does that sound like a reasonable way to proceed?


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[Guyfang]

You can open the oil fill on any engine and have oil mist coming out when running. Taking out the 4in long dip stick and having oil mist come out is totaly normal. By pulling the dip stick tube you would be removing any vacuum.

Removing a part and expecting the engine to run per spec is not going to happen.

Thats why to piece of paper or plastic will be sucked back down to the dip stick hole when you do the quiet and dirty test. Your closing a hole in the system.

 

[Chainbreaker]

...I know I don’t run it often enough or hard enough...


Here’s my plan of action:

1) Build a break out electrical box that I can plug into the generator and have something to load test it. All I have now is the house which doesn’t work too well.

Regarding # 1 on your list. A nice easy load tester can be had by using a 240V garage heater such as the type sold at Northern Tool or Rural King. Its fairly small & compact and provides a balanced load on each 120V leg of 240V. When not using as a load tester you can even use it as a garage heater!

Example of a 5 / 7.5 Kw unit: [URL="https://www.northerntool.com/shop/tools/product_200631888_200631888[/URL]