(800) 853-2651
SHOP NOW

MH33/44 Injection Pump

M

MFJohn

Member
I have a MH 33 diesel with an American Bosch PSB injection pump. Does anybody know if when the marked gear tooth lines up with the "0" mark on the pump housing (this is necessary to remove/install pump head), the timing line on the pump hub (viewable through the timing window) should line up with the timing pointer? According to instructions in past posts on this forum, sometimes the marked gear is supposed to line up with the "0" when the timing line is lined up with the pointer, and sometimes it's supossed to be one gear tooth off. (I found the pump adjusted one tooth off.)
I've got the pump reassembled so both lines line-up at the same time and the engine runs OK, but I'm thinking that maybe intead of running 24 BTDC, I'm running closer to 30 BTDC.
I've seen recommendations to do it both ways in past posts on this forum. Maybe it depends on the engine?
Then again, if somebody can tell me how to adjust the timing by looking at the exhaust and monitoring the rpm, I'll just do it that way and call it good enough.
 
With hub mark aligned with pointer the head marked tooth will be one tooth past the housing mark when head is installed correctly. Head is installed with tappet at base circle of cam lobe, just starting to lift the tappet. When hub mark and pointer line up tappet has started up the cam ramp. this will be port closing, begining of injection. My IT MH book shows it wrong, but my IT Oliver 77, 88, 99 has it right.
 
Forgot to mention, changing head drive gear tooth position will NOT change the timing, hub mark to flywheel does. Moving head gear controls port alignment to correct cylinder injector. Make sure the head plunger drive in the gear is good. If cracked or broken cylinder phase timing will be off far enough to keep it from running.
 
Interesting... It appears to run OK with the head gear off one tooth. there must be enough of a plunger/port overlap to still allow the nozzles to work properly. Nuts. I'll have to pull the pump (again!) to reposition the quill shaft. I'll let you know how it turns out in the end. Thanks!
 
Just pull the head and move the drive gear one tooth. Head and quill shaft are installed at same cam location, with tappet just beginning to start up ramp but still on base circle. This is when quill gear cutout should be to install head with tooth notch lined with housing mark. Even if quill is in wrong, find where head will lift out and move one tooth. No need to remove complete pump.
 
Good idea. By the way, checking the American Bosch manuals I have, for the PSB pump models with the internal spring governor, the head is timed like I have it now. (I incorrectly used that procedure to reassemble the pump.) For the models with the external governor, they're "timed to port closing" like you said.
 
If I just pull the head to change the timing, I can fix the quill shaft to head timing, but then the pump to engine timing will be incorrect (as indicated by the timing line and pointer). I pulled the pump and corrected the quill shaft to head timing. Now all the timing marks will line up like you said. After reassembly, the engine seems to run the same as before the change, but it"s probably easier on the pump to have the port opening correctly synced with the plunger stroke. Thanks for your help.
 
You must log in or register to reply here.

Similar threads

J
john deere 2040 injection pump removal.
Replies
8
Views
528
Keith Molden
K
A
Roosa Master Injection Pump JD 310B Timing Question
Replies
3
Views
177
AliasRex
A
R
Massey 1150 can't get fuel through injection pump?
Replies
4
Views
331
Dieseltech
D
S
Old 350d c series injection pump crank no start.
Replies
0
Views
137
Scotty2track
S
B
Farmall 686 D312 injector pump timing
Replies
3
Views
211
Bkpigs
B
Tractor Parts Tractor Manuals

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Copyright © 1997-2024 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters
Website Accessibility Policy

Back
Top