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9U D6 Engine Overhaul

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3 years 8 months ago #224754 by Xtremist
Hey

I was wondering where the best place would be to buy some parts to overhaul the engine in my D6, im going to do a balance test on it right away but i have a feeling that i have 3 cold cylinders, changing injectors and plungers didnt help much.

thanks for the help

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3 years 8 months ago #224755 by kracked1
Replied by kracked1 on topic 9U D6 Engine Overhaul
Is it getting up to temp? Has it been worked hard recently?

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3 years 8 months ago #224757 by Ray54
Replied by Ray54 on topic 9U D6 Engine Overhaul
Without major blow by or oil consumption I would say look at the fuel system. What RPM is the engine running. Back 40 years ago I put a kit in one really did nothing. Had old guy check it out it was not running up to 1600 so we speeded it up, over shot the mark and ran it about 1700 high idle. Made a different tractor out of it.
At first Cat had them at 1400, but turned them up to 1600 latter on. The 318 engine in the DW 10 scraper was turned up over 2000 if I am not confused again. They did have a different governor and other parts on the engine made for the scrapers. But proves the bottom end can stand more RPM than the setting used in the D6.

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3 years 8 months ago #224763 by Xtremist
Replied by Xtremist on topic 9U D6 Engine Overhaul

Without major blow by or oil consumption I would say look at the fuel system. What RPM is the engine running. Back 40 years ago I put a kit in one really did nothing. Had old guy check it out it was not running up to 1600 so we speeded it up, over shot the mark and ran it about 1700 high idle. Made a different tractor out of it.
At first Cat had them at 1400, but turned them up to 1600 latter on. The 318 engine in the DW 10 scraper was turned up over 2000 if I am not confused again. They did have a different governor and other parts on the engine made for the scrapers. But proves the bottom end can stand more RPM than the setting used in the D6.



i just picked this dozer up, it was hard to pass up the deal imo.... therers a parts cat and a good cat all for 3k.... the good cat is really straight (serial number is 9U2564), undercarriage is all nearly brand new, has upgraded solid front idlers, has been upgraded to an oil clutch, hardnose with hydraulics, direct electric start, winch, etc. It also isnt beat up and all the guards and pans are there. It has a really bad miss and smokes terribly but i was aware of that going into the deal. Its only running on 3 out of 6 cylinders, the smoke totally disappears if i crack all 3 of the "bad" plunger lines and the engine rpm doesnt change a bit to crack those lines. But your also right we havnt totally ruled out fuel problems but figured since my father has the equipment needed to do a balance test id start with that and see what it shows.

Can anyone give me the proper specs to set the valves on the engine ? I tried to google it but everywhere i looked there is a different answer it seems.

Is it worth it to set the governor to the higher rpm ? didnt the later 9u models have a bit higher horse output, im assuming this was just different settings/adjustments made to the fuel system, is it worth while to turn it up to those settings (after the issues are taken care of, of course)

thanks for the info !
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3 years 8 months ago #224764 by edb
Replied by edb on topic 9U D6 Engine Overhaul
Suggest that if you have not yet done so to adjust the valve lash and get the injection pump lifter settings checked.
I know of overhauled engines that ran no better after overhaul than before due to incorrect lifter settings.
Cheers,
Eddie B.

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3 years 8 months ago #224765 by Xtremist
Replied by Xtremist on topic 9U D6 Engine Overhaul

Suggest that if you have not yet done so to adjust the valve lash and get the injection pump lifter settings checked.
I know of overhauled engines that ran no better after overhaul than before due to incorrect lifter settings.
Cheers,
Eddie B.



can you give me all those specs, if you read my above post ive tried to find them with not much luck, seems like theres a different answer wherever i look.... thanks, i appreciate the help !

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3 years 8 months ago #224767 by edb
Replied by edb on topic 9U D6 Engine Overhaul
Hi,
looks like you posted that one while I was typing my answer so missed it.
Valve lash for both Inlet and Exhaust is 0.010" hot--adjust to around 0.012" initially cold seems to work and recheck when hot.
Also check the Inlet valve decompression system has clearance and so to be sure it is not holding the inlet valve off its seat--this clearance to the cutout on the decompression rod is about 0.125" ---this clearance is not adjustable and is a result of that all inlet valve train components are as per factory specs. this clearance may be found to be reduced usually when the inlet valve has recessed into the head --some clearance is required.

Lifter setting is 1.736" measured from top surface of the injection pump housing to the lifter yoke pad. This is done with the relevant piston at Top Dead center compression stroke---if you go past TDC turn the engine back at least 60 Degrees and come up to TDC again so as to remove any slack in the timing gear train.
TDC marks and pointer are on the front face of the flywheel as viewed thru the opening under a two bolt cover on the front right face of the flywheel housing--be aware the stamped marks will be hard to find as they will be covered by and filled by crud on the flywheel face.
Hope this helps.

Cheers,
Eddie B.
The following user(s) said Thank You: Xtremist

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3 years 8 months ago #224779 by Ray54
Replied by Ray54 on topic 9U D6 Engine Overhaul
Before things go sideways, is the 318 engine one of the ones that the flywheel can get out of sink with the marks? Or is it late enough that the flywheel only goes on the one way. With all the late model updates this could well be a machine that has had a lot of work done to it over time. This increases the chance of the flywheel having been off.

You don't say which 3 are not firing. But by chance is it the front 3? That would indicate linkage trouble with the compression release mechanism. Because the valve cover is 2 pieces and I don't remember how it all connects together. But if the valves are held open that would explain your problem. Just a random thought that would be easy to check. But I fear with the poorer quality of "new" diesel fuel, fuel problems will become more common.

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3 years 8 months ago - 3 years 8 months ago #224780 by edb
Replied by edb on topic 9U D6 Engine Overhaul
Hi Team,
yes, the D318 is also one of the engines that can have the flywheel out of sync with the crank--there are Factory chisel marks on both the flywheel and the crank that need to be aligned at assembly.
If the flywheel is out of sync then you need to establish your own TDC positions for the 3 required positions of crankshaft TDC--ie-- 1&6, 3&4, 2&5. or remove and refit the flywheel in the correct timed/sync position.
Cheers,
Eddie B.
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Last edit: 3 years 8 months ago by edb.

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3 years 8 months ago #224788 by wimmera farmer
Another little stumbling block at least on a 9U here. The same flywheel is used for a 4 cylinder and a 6 cylinder engine and has dual set of timing marks that are confusing when first come across. cheers WF
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