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Yanmar mp4 4tnv98 help

Birken Vogt

Charter Member
Joined
Nov 30, 2003
Messages
5,805
Location
Grass Valley, Ca
If I understand correctly I asked about this pump in another thread, I think Yanmar made it themselves and TPG says it is not such a great design anyway?
 

thepumpguysc

Senior Member
Joined
Mar 18, 2010
Messages
8,522
Location
Sunny South Carolina
Occupation
Master Inj.Pump rebuilder
rmll> in the 1st pic of the front of the pump.. I can SEE the timing mark.. its right inline w. the key..
small "dash" on the pump housing.. you should be on the right cyl.??
 

DIESELMAN3500

Member
Joined
Jul 2, 2024
Messages
23
Location
NJ
Hey hef im pullin my hair out tonight Got a 4 cyl yanmar. injection pump gear was removed and was given pump seperate from engine. They pulled four bolts instead of large nut. I reringed and resealed engine. When all timing marks are aligned for pump gear, crank and ,cam. the cylinder closest to timing cover both rocker arms are loose. Which according to manual is cylinder 4 and is on tdc. How do I know injection pump is on the right cylinder? I can measure the plunger to set precisely set timing with a dial indicator. But that could be on any of the four output lines if im understanding this. And once I firgue out where to have pump what cylinder does it fire to? Looks like cylinder 4 which is closest to timing cover if im reading this right. Thanks hef
hey rmll did you ever get this sorted out? does the pump have a mark for #1 TDC?
 

FixingTractors

New Member
Joined
Jul 10, 2026
Messages
4
Location
California
I have read this thread a couple times. Im still a bit confused, and seeking more details. I will add pictures. What is the correlation between the keyway on the injection pump to the injection pump drive gear? I have a similar situation, full engine rebuild and unfortunately injection pump gear was taken off.
How do i determine tdc #1 on pump? I have not identified any markings yet.
 

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FixingTractors

New Member
Joined
Jul 10, 2026
Messages
4
Location
California
I have read this thread a couple times. Im still a bit confused, and seeking more details. I will add pictures. What is the correlation between the keyway on the injection pump to the injection pump drive gear? I have a similar situation, full engine rebuild and unfortunately injection pump gear was taken off.
How do i determine tdc #1 on pump? I have not identified any markings yet.
This is a rebuild on a john deere 110 TLB. (4TNV98-MJTLB
 

mg2361

Senior Member
Joined
Jul 5, 2016
Messages
6,798
Location
Pennsylvania
Occupation
Equipment Mechanic
Welcome to HEF Fixing Tractors;)!

The machine's serial number is always helpful. The serial break has different injection pumps.

Check your messages (based on your photos).
 

mekanik

Senior Member
Joined
Aug 20, 2015
Messages
1,462
Location
Canada's Northwest
I rebuilt a Yanmar 4TNV a couple years ago. If I remember correctly there is a timing pin that goes through a hole in the gear then through a slot in the pump drive flange and into the front face of the pump while the engine is at TDC. I think I used a metric drill bit.
 
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