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7020 Overhaul or used motor?

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
Printed Date: 12 Jul 2020 at 1:21am
Software Version: Web Wiz Forums 11.10 -

Topic: 7020 Overhaul or used motor?
Posted By: Blustery Knoll Farm
Subject: 7020 Overhaul or used motor?
Date Posted: 06 Dec 2018 at 10:37pm
I finally got a chance to tear into the motor on my 7020 PD. Here's the thread from this spring when things went south. I found that the bearing on rod #6 was spun. That explains the clattering for sure." rel="nofollow -

So, should I do a complete overhaul on the motor, or am I likely better off hunting down a used motor? The tractor is in fair condition, but it's definitely fairly high houred.

Posted By: ryan(IN)
Date Posted: 07 Dec 2018 at 6:26am
If you overhaul it you know what you got. Getting a another motor is a crap shoot because it could have the same problems. I vote overhaul it and you will have a motor that’s lasts you a long time.

1984 8070 FWA,1979 7060,1975 7040,1971 190,1960 D-17D,1957 D-14, 196? D-19G, 1975 5040,1971? 160,1994 R62

Posted By: tornado8070
Date Posted: 07 Dec 2018 at 6:29am
Overhaul what you have. Otherwise you may end up with some else’s junk.

09’ DT205B, 08’ DT220A, 83' 8070 MFWD, 83’ 8070 85’ 8050 MFWD, 83' 8030, 82' 8010, 85’ 6080 MFWD, 84’ 6080, 79' 7020, 85' M3 RWD, 85' 920 diesel,AC C-50 forklift.

Posted By: Lonn
Date Posted: 07 Dec 2018 at 7:10am
A used motor would probably come from a combine so there would be a lot of labor to make the switch.

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Posted By: DrAllis
Date Posted: 07 Dec 2018 at 7:22am
You have a bigger problem than just overhauling it. You will need a crankshaft. Almost anytime there is a rod bearing failure in any brands high output turbo diesel engines, the crankshaft will be unfit to be reground due to cracks or the journal losing its Rockwell hardness. Find a running engine and overhaul it.

Posted By: Hurst
Date Posted: 07 Dec 2018 at 7:32am
Did you find your antifreeze leak?  While you have it apart, get your head checked over with a fine tooth comb by a reputable machine shop.  There's not a lot of material between the injector opening and the valves on the copper sleeved heads, so they like to crack there if the motor has been hot.  If your head looks good, I'd consider reusing it with all new copper sleeves and a valvetrain overhaul.  I believe the sleeves are available aftermarket now.  If your head has a crack, replace it with a D2900 head from an earlier tractor without the copper sleeves, if that is compatible with the 7020's intercooler connections (someone else can chime in on this).  As far as the motor, I would rebuild if the crank is still usable.  Otherwise, I would look for either a good std/std crank to put in your motor or a used low hour late 301 you can swap parts onto and rebuild it or if it is in really good shape, just freshen it up with at least new o-rings on the sleeves and bearings.  I don't think the 301 crank has a lot of meat to machine off compared to some of the other engines, but I don't have my service manual in front of me to see what the max was.  Just my 2 cents.  Easy for me to type when I'm not paying... so definitely do what you need to do to fit in your budget.


1979 Allis Chalmers 7000
5800 Hours

Posted By: Blustery Knoll Farm
Date Posted: 07 Dec 2018 at 9:49am
Well, I have found two running M2 combine motors for $2250-2500. Seems tempting to just drop them in and go.

Posted By: Acdiesel
Date Posted: 07 Dec 2018 at 10:45am
you could buy the used engine, pull the pan and put some new bearings in it before you install it.
overhaul kit is around $1200  plus head work

just a thought.


D19 diesel,D17 diesel serIII D14 NF D14 WF, D15 ser II,
D15 SER.II DIESEL two 720's

D17 ser.4, D14 oliver 77
Gmc trucks,caterpillar
I'm a pharmacist (farm assist) with a PHD (post hole digger)

Posted By: DSeries4
Date Posted: 07 Dec 2018 at 9:27pm
Originally posted by Blustery Knoll Farm Blustery Knoll Farm wrote:

Well, I have found two running M2 combine motors for $2250-2500. Seems tempting to just drop them in and go.

Combine engines are NOT a drop in and go.  Quite a few parts need to be switched from the tractor engine.  As Dr. Allis said, going with a used combine engine I would still rebuild it before putting it in the tractor.  It is still a 30 year old engine that you do not know anything about.

'49 G, '54 WD45, '57 WD45, '58 D14, '59 D14, '61 D15D, '66 D15II, '66 D21II, '67 D17IV, '67 D17IVD, '67 190XTD, '73 620, '76 185, '77 175, '85 6080

Posted By: DrAllis
Date Posted: 07 Dec 2018 at 9:56pm
Technically, it would take an M-3 engine @ 145 flywheel HP (intercooler) to match the 7020 engine for performance.  The majority of M-2's are @130 flywheel HP like a 7010 tractor. On the plus side, the 7020 doesn't have a hydraulic pump on the engine, so getting a combine engine to "fit" might only take making a couple of ears to weld or bolt to the timing covers front plate to attach it to the tractors side frames.

Posted By: Blustery Knoll Farm
Date Posted: 07 Dec 2018 at 10:27pm
I'm waiting to hear back from my machine shop guy about cost of an overhaul before I make a decision. I swapped a combine motor into an old Farmall a couple winter's ago, so I'm accustomed to there being some differences between the engines.

I know that a complete overhaul is the "best" way to go, but the rest of the tractor isn't exactly cherry, so it's hard to spend almost what it would cost to just buy another tractor.

Date Posted: 08 Dec 2018 at 8:14am
Does anyone know if a new crank is available for that engine,or any ALLIS engine for that matter? To the OP, I hope everything works out for you,I always wanted a 7020 myself.

Posted By: tbran
Date Posted: 08 Dec 2018 at 8:37am
We have done this before, Doc covered the front mounts, all one has to do is swap the cooling system / intercooler / water pump / flywheel / & most time front pulley. Most combines have around 2000/3000 hours. How many engines need overhauling at this time? Look at the donor engine - pull the valve cover or look at blow by tube for signs of antifreeze - after sitting for a day - pull the oil drain hose cap and drain out about a qt of oil and look for antifreeze. IF all ok then by all means crank the engine and look for blowby - if it runs fine - most will - go for it. Remember - 100% of all tractors run 100% on used parts.

When told "it's not the money,it's the principle", remember, it's always the money..

Posted By: exSW
Date Posted: 09 Dec 2018 at 1:59pm
My 7010PS has a combine engine now. Came to me that way. If it goes I've got a 12valve 5.9 Cummins here. Just saying.

Posted By: Michael V (NM)
Date Posted: 09 Dec 2018 at 6:18pm
Hav ya checked with All States Ag Parts?? Their used engines come with a 1 year warranty...might be something to check out...

Posted By: Blustery Knoll Farm
Date Posted: 09 Dec 2018 at 7:55pm
Michael, I have not. That's good information to know.

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