Gotta pull the Head

[Selkirk_D]

So I’ve pretty much determined that I have to pull the head on my L2850. It’s smoked since I got it and a thermal scan indicates that #1 cylinder is not completing its burn. Reviewing dealer notes revealed that a leak down test showed 70% out the exhaust valve on #1. Valve lash checks out fine. No indication of crack or head gasket leakage into coolant, no coolant loss, no oil loss, no water in oil. Best case, valve seat needs touch up and possibly new valve.

Now for my question: I’m contemplating pulling the pan and replacing rings and rod bearings too, “Just Because”, even though at 2500 hours, the v-1702 runs and sounds fine. Would today’s factory parts be worth the extra price, or are they now Chinese/Indian too? Are aftermarket rings bearings decent quality? Or if all looks good, should I just leave well enough alone and not mess with the Japanese originals?

 

[North Idaho Wolfman]

You haven't done a compression test?
I would do that before anything else, it will give you a baseline on the whole engine.
If you pull the head and there is any damage to the piston or the cylinder it's not always a simple as just replacing parts and if you're in it that far you should do everything.
And yes that require pulling the motor.
Sending it to a machine shop having the sleeves pressed out new ones pressed in and bored to size.
Get a full rebuild kit and throw out the head gasket, use OEM for that.
There are several different V1702's, you need a rebuild kit for a V1702-DI-A
If you get a kit for a V1702-IDI nothing will fit.
The pistons are directional as are the rods and also don't swap them in the cylinder location either, several of these older engines have a different rod in one location.

Kubota parts are better in some cases, but due to the age and price aftermarket will be fine.

 

[Selkirk_D]

I’ll do a compression test for reference before I pull anything but the dealers notes already pointed to the exhaust valve on #1 as having a problem. So the head has to come off no matter what.

 

[John T]

Personally, I wouldn't touch the Bottom end.

 

[Selkirk_D]

Thanks all, I appreciate the inputs. The Japanese got to the top of the quality heap in the 70’s & 80’s using several ingenious techniques. One of my favorites was identifying key components that are critical to longevity and reliability. Then they’d study improving those components through design and materials. If they could spend $2 more on a new design part and significantly increase reliability, they’d do it, and just charge $2 more for the vehicle. I believe that rings are just such a part, and I’m hesitant to replace them unless the aftermarket rings are known to be equal or better to oem. Hyundai has major issues with their cars being able to make it out of warranty because they cheaped out on the rings. I may still pull the pistons out to verify that rings are in good shape and not stuck or carboned up.

 

[North Idaho Wolfman]

Thanks all, I appreciate the inputs. The Japanese got to the top of the quality heap in the 70’s & 80’s using several ingenious techniques. One of my favorites was identifying key components that are critical to longevity and reliability. Then they’d study improving those components through design and materials. If they could spend $2 more on a new design part and significantly increase reliability, they’d do it, and just charge $2 more for the vehicle. I believe that rings are just such a part, and I’m hesitant to replace them unless the aftermarket rings are known to be equal or better to oem. Hyundai has major issues with their cars being able to make it out of warranty because they cheaped out on the rings. I may still pull the pistons out to verify that rings are in good shape and not stuck or carboned up.

A compression test will tell you if you need to worry about the rings and or cylinder wear issues.

 

[Selkirk_D]

As will visual inspection. If I’m close to 400 psi. I’ll pass on further disassembly , but #1 will likely be closer to 200 if I’m lucky, so compression test on #1 won’t tell me much about the rings.

 

[Henro]

I’ll do a compression test for reference before I pull anything but the dealers notes already pointed to the exhaust valve on #1 as having a problem. So the head has to come off no matter what.

Probably a simplistic question, but how would the dealer determine that the issue was with the exhaust valve rather than the intake valve?

I mean, both need to be sealed to maintain compression, right?

 

[Selkirk_D]

When they do a leak down test and air is escaping via the exhaust port. They had exhaust manifold off when they did it. Also unnecessarily replaced injector #1 so the previous owner got the pleasure of spending $750 to find out there’s low compression in #1. This is exactly why wolf man says to do compression check first! Also exactly why I’ll never take this tractor to the dealer for repairs unless I absolutely have to.

 

[John T]

Also unnecessarily replaced injector #1 so the previous owner got the pleasure of spending $750 to find out there’s low compression in #1. This is exactly why wolf man says to do compression check first! Also exactly why I’ll never take this tractor to the dealer for repairs unless I absolutely have to.

I see that all the time with newer big trucks with emissions problems..
CEL code says it could be 5 different things..... "lets just start throwing parts at it and see what works"

$4000 later you get the truck back and next week it does the same thing..

it's all a big scam and a lot of the new breed "techs" don't know which way to turn a screw driver unless it's spelled out for them..

ok I'm off the soapbox...

 

[Selkirk_D]

Exactly! Most techs, like doctors, suck at troubleshooting. But sometimes I think there’s some intent there for the techs to puff up the bill. Also not a fan of “flat rate” books where you get charged 5 hours labor for 2 hours of work. Interestingly, virtually all the problems with my ram/cummins have been emissions related. Expensive and aggravating, but I fixed them.

 

[nota4re]

Personally, I wouldn't touch the Bottom end.

Agree. Only if there was a known weak point that you might as well resolve when head is off, otherwise don't fix what ain't broke!

 

[Selkirk_D]

So I finally got around to pulling the head. First I ran a compression test:
#1: 310 psi
#2: 300 psi
#3: 365 psi
#4: 345 psi

Chicom compression tester accuracy is unverified and somewhat suspect since the engine started easy and ran great other than smoking a bit. No sign of head gasket failures or head damage. Cylinders look good, but I’ve yet to pop any pistons out . #1 seems to be the main culprit as evidenced by the excessive soot and carbon on the head and especially in the exhaust port. Wondering if I have some stuck rings.

 

[North Idaho Wolfman]

Bad or stuck rings or bad injectors.

Excuse my cartoon writing, in a hurry

 

[Selkirk_D]

Thanks again Wolfman. Dealer replaced #1 injector with oem. They also supposedly replaced all the valve guide seals. I’m going to start with cleaning and checking #1 valve guides and seats. Tons of soot in the #1 exhaust port. I’ll pop out the pistons once I remove the driveshaft and pan.

 

[Selkirk_D]

So quick question: Do I have to unbolt the front axle to get the pan off or can I shift the pan back enough to clear the front pinion housing?

 

[North Idaho Wolfman]

So quick question: Do I have to unbolt the front axle to get the pan off or can I shift the pan back enough to clear the front pinion housing?

If I remember right you will have to drop the front Frame (axle included) to get the pan off.

 

[Selkirk_D]

Good thing they made it easy to work on…..not. No wonder the Japs lost the war!

 

[ruger1980]

Can you send pics of the cylinders? I would try to avoid mulling the pistons unless absolutely necessary.
I would clean, disassemble and inspect the head before going further. It looks you may have a cracked head between each of the valves but you need to inspect them closely. See below

 

[#40Fan]

Can you send pics of the cylinders? I would try to avoid mulling the pistons unless absolutely necessary.
I would clean, disassemble and inspect the head before going further. It looks you may have a cracked head between each of the valves but you need to inspect them closely. See below
View attachment 151314

I think that is just an optical illusion even though they look wet. There is a depression there for the injector.