Finally bought a MEP-831a

[AfghanVeteran2010]

Thank You DieselAddict,

I order a new set of valves as well as springs. I'm not exactly sure what you mean by "dress the valve seats". Do you mean lap with grinding compound or a valve grinding tool?

 

[rustystud]

Thank You DieselAddict,

I order a new set of valves as well as springs. I'm not exactly sure what you mean by "dress the valve seats". Do you mean lap with grinding compound or a valve grinding tool?

You can "lap" the valve to the seat with Lapping compound, or you can take the engine to a small engine repair place and they can use a seat grinder on them. Those valves of yours probably can be saved. If you take it to a shop they can determine if the valves can take a grinding or not. As far as the small scratches on the block, don't worry. As long as the gasket can seal they will be fine. About using water to clean the engine. I never use water or soap. I use lacquer thinner and brake-cleaner, or as we say in the shop "steam cleaner in a can" . Then use shop air to blow everything dry.
Your doing a fine job here ! Your engine will soon be purring along !

 

[DieselAddict]

If the valve seat area looks ok you may not have to have it ground. Its important that the area be smooth and flat (no rings or grooves or pitting).

The valve seat and the valve itself are ground on different angles to ensure they fit together tightly to form a seal. Lapping is used to broaden the contact area to the right size for proper valve cooling. It is not used to create a totally mated surface.

Most valves now are induction hardened and as such they depth of the hard material is not very thick. Its not recommended to grind induction hardened valves since you will grind away the hardened material and leave a softer surface that will wear faster. Ordering new valves is the recommended path forward.

 

[AfghanVeteran2010]

Thanks Rustystud and DieselAddict
I cleaned the valve seats today, the exhaust valve seat is scratched up a bit. I do have a brand new set of valves on the way. I think it needs to be ground, is it something that I can do?

 

[DieselAddict]

The photos on the forum lack the resolution to really tell but I don't see anything there that looks bad.

Grinding seats requires some specialized equipment to do right. Possible to do, sure. I don't think it's practical to do for two valves.

If it needs work I would take it to a machine shop with the valves and let them do it.

 

[rustystud]

If the valve seat area looks ok you may not have to have it ground. Its important that the area be smooth and flat (no rings or grooves or pitting).

The valve seat and the valve itself are ground on different angles to ensure they fit together tightly to form a seal. Lapping is used to broaden the contact area to the right size for proper valve cooling. It is not used to create a totally mated surface.

Most valves now are induction hardened and as such they depth of the hard material is not very thick. Its not recommended to grind induction hardened valves since you will grind away the hardened material and leave a softer surface that will wear faster. Ordering new valves is the recommended path forward.

That part about lapping is not correct. Lapping is the oldest way to get a true positive seal between the valve and seat. Also most all production valve seats are made with "powder metallurgy" . This allows the manufacturer to precisely match their valves and seats with the head material used. So a cast-iron head will have one type of seat material, while an aluminum head will have another . This also allows the seats to have the same heat characteristics as the heads. Also most diesel manufacturers have not used "induction" hardened valves for some time now. In fact Cummins is using a valve and seat made from "Tribaloy" . In valve seats, powder MET is the new thing ( since around 2002) which is what "Yanmar" uses in all their aluminum head diesel engines.

 

[rustystud]

Thanks Rustystud and DieselAddict
I cleaned the valve seats today, the exhaust valve seat is scratched up a bit. I do have a brand new set of valves on the way. I think it needs to be ground, is it something that I can do?

View attachment 692475View attachment 692476View attachment 692477View attachment 692478View attachment 692479

In all honesty, get some good lapping compound and go after them. The seats don't look bad at all, and a little lapping will bring them right up to spec !

 

[AfghanVeteran2010]

This is the items I bought the other day to lap valves.

 

[rustystud]

This is the items I bought the other day to lap valves.

View attachment 692575

Now all that is required is a little "elbow grease" !!! So get after those valves !
Oh, and when you get your engine running a little video would be great !

 

[AfghanVeteran2010]

Valves and springs are here, valve seal pliers/installer will be here tomorrow. So I should be able to have the head assembled in a few days.



I will upload a video when I get it up and running.

Thanks

 

[DieselAddict]

That part about lapping is not correct. Lapping is the oldest way to get a true positive seal between the valve and seat. Also most all production valve seats are made with "powder metallurgy" . This allows the manufacturer to precisely match their valves and seats with the head material used. So a cast-iron head will have one type of seat material, while an aluminum head will have another . This also allows the seats to have the same heat characteristics as the heads. Also most diesel manufacturers have not used "induction" hardened valves for some time now. In fact Cummins is using a valve and seat made from "Tribaloy" . In valve seats, powder MET is the new thing ( since around 2002) which is what "Yanmar" uses in all their aluminum head diesel engines.

Can you expand on the lapping comment? We were always taught to lap the valves until you have the correct width contact area (verified by bluing) then stop. You don't lap a valve until it completely covers the seat. That leaves no room for it to wear in over time.

 

[AfghanVeteran2010]

We were always taught to lap the valves until you have the correct width contact area (verified by bluing) then stop.

I plan to do that, instead of bluing I want to use dry erase marker. I have been looking at YouTube on how to do this, practically every video out there contradicts each other. That's YouTube right lol

EDIT I'm fairly sure how to lap the valves

 

[AfghanVeteran2010]

I lapped the valves hopefully correctly. Spent about 2 mins on each valve. My dry erase marker was dried up, I will pick up a kit tomorrow if need be.

Measurements
Intake valve 1.94mm(wear pattern) intake seat 1.79mm
Exhaust valve 1.75mm(wear pattern) exhaust seat 1.70mm

 

[DieselAddict]

Looks good to me.

 

[AfghanVeteran2010]

Looks good to me.

Cool, I thought I might of messed it up. Thanks

 

[AfghanVeteran2010]

I'm curious if anyone else has had issues with their muffler nuts becoming lose from operating vibrations. If so I came across a product that seems to hold together for the 8 hrs I was able to test them, before having to tear down engine. NORD-LOCK NL8SP VIBRATION PROOF LOCK WASHER 5/16" paired with M8 x 1.25mm Locking Flange Nut Black Oxide Hex Exhaust Manifold Nut.



When I installed these previously the stud was short by a few millimeters, this in turn causes the locking action of the (Locking Flange Nut) to not be effective by itself. A longer stud would have to be installed to accommodate the Locking Nut(Stock stud is a M8x 1. The Nord-Lock washer as far as I could and can tell it held up very effectively. It takes a far amount of force to remove (reason covered in video).


https://www.youtube.com/watch?v=IKwWu2w1gGk

After reading a report of what can happen if the muffler works its self lose, I decided to search for a solution to solve this. Report follows.
Model No.–MEP 831A – 3kWSerial No.–FZA15746 At 850 hours, the muffler bolts failed on the exhaust system causing excessive vibration and broke the muffler off from the exhaust pipe where the two were welded together (Figure 3).The entire exhaust system was replaced. Total repair time was approximately 6 hours.

Figure 3. Muffler and Header Pipe Showing Broken Welds as a Result of the Muffler Bolt Failure

 

[AfghanVeteran2010]

I assembled the valves today

 

[Another Ahab]

I assembled the valves today
View attachment 693106View attachment 693107

Very clean, very nice!

 

[AfghanVeteran2010]

Has anyone tried removing their exhaust studs? Thinking about replacing with M8 x 1.25mm x 35mm Alloy Steel Exhaust Manifold Studs. The 35mm length might not be enough won't know till I remove them. The stock studs are M8X 18, the 18mm is what is exposed. I plan to extract studs with double nut.

 

[AfghanVeteran2010]

Okay never mind these are easy to remove, removed both with no issues. 35mm should do nicely