4620 engine rebuild

[Ireland.29]

I will probably need to do some engine work in 2012 and I need some help from you guys to figure out what I need to do.. The engine is dyno"ing at 139 so power not a problem but it does smoke a lot before the turbo kicks in, it uses about 1 gallon of oil per 60 hours and starts very hard when cold, its already got new injectors and IP. Oil pressure starts out around 45 and drops to 25 when very hot (at idle) but it holds over 40 all the time at 1700-1800rpm.. so I know I will need to take the head to a shop to test specs but what should I do with the engine - how do you decide on in frame vs overhaul? and would replacing bearings without touching the crank do anything for oil pressure? (even though i guess its not too bad as it is?) and do you guys do any work on camshafts during rebuild? thanks in advance!

 

[buickanddeere]

Try straight 40 weight oil and a turbo rebuild first. You may save thousands of bucks.

 

[Ireland.29]

thanks buickanddeere .. How will that help the poor starting though? it definately looks like ring / liner wear but im open to correction. How do the oil pressure specs look? Im thinking its ok with existing deere 15w40 engine oil for now?

 

[Kent Petersen]

you can check turbo by pulling the pipe off at the intake and see if you are getting oil in there if you over haul put in new cam and oil pump drive gear in and new brgs you need to get the valve seats back to factory specs very importten for starting i have done almost all rebuilds as in frame on about 250 of the 404 engines over the last 40 years works good

 

[larryanderson]

Some of the symptoms you describe are fairly normal for a 4620.You didnt say the hours or if it had much blowby which is a good indicator.Some JD dealerships push for underhauls but many dont.Trucks were thought to need new bearings 20 yrs ago but it is not talked about much lately.Before I would spend 5/10K on a tractor that is worth less than 12K I would really have to like it because you will have to keep it to get much return on your investment.Some newer tractors use a quart of oil a day and the dealerships arent concerned .Good Luck

 

[tim s]

I agree with B&D, the straight 30 or 40 weight oil will have a bit different viscosity than 15-40, even though the claims say they don't. your turbo could also be letting some oil past the seals and sending it in with the charge air,along with a weaker boost level. They were a bit hard starting from the beginning...it would be worth the effort to try...

 

[Tx Jim]

I would recommend checking engine compression. If it's low then that would contribute to the hard starting. Are you sure inj pump is timed correctly??

This overhaul kit costs $1830 from JD & 6 R66452 rod bolts costs #10.51 ea. RG27926 ENGINE OVERHAUL KIT 1 (PISTONS MARKED AR50624, AR50940 OR RE67932) (CONTAINS (6) RE69393 PISTON LINERS, GASKET KIT, STD BEARINGS, FRONT/REAR SEALS AND SNAP RINGS) (ALSO ORDER R66452 ROD BOLTS) (SUB FOR RG21340, RG23435 OR RG26464)

JD recommends an underhaul(rod/main brgs & rod bolts) & torsion dampner at approximately 5000 hrs of use.

 

[Ireland.29]

thanks for replies guys... there is a LOT of blow-by if im honest, also there is a (very slight) leak from front crank seal which I think might stop if it were not for the blowby. This is mostly a parade tractor so is worth a lot more here than if it were a working tractor in canada / USA.... its showing 5000 hours but im thinking it may have gone around and it might be 15000?

 

[tim s]

I never went for the "bottom" end O/H, besides getting oil in your eye's and ruining a shirt, it seemed that the bearing wear is not as big of issue as scuffing pistons and failing liner o-rings, all the way top to bottom,end to end..is the best way.An old guy told me once that a partial O/H was like cutting a puppy's tail off a little at a time so it don't hurt so much...

 

[Tx Jim]

Tim
I agree and JD dealers probably promotes an underhaul to sell parts/labor.

What is your opinion on replacing the harmonic balancer(torsion dampner) at 5000 hrs even if it looks good to go?

 

[tim s]

Save the money, as long as the rubber sleeve is not suffering it's still good, when the get oil soaked they start to deteriorate, allowing the outer ring to slip on the hub,"then" they are bad...as long as they are in place on the hub there is no problem with them.

 

[Ireland.29]

I wouldnt consider an underhaul by itself because I dont think my main problem is the lower end, due to starting and blow by it looks like top end to me... Im hoping if I do a complete overhaul that i can get away with bearings and not need to grind crankshaft? oil pressure holds at 40 at high idle but down to 25 at idle when worked hard..

 

[fixerupper]

Don't know what you're finances are like, but I'd consider doing an inframe. You aren't using a gallon a DAY yet but it sounds like it's not that far off. Freshening up the head to give it good compression might make it use even more oil. I was in the same situation a year ago with a 4650. It wasn't using oil bad but the head gasket was bad. When the head was off I saw some discoloration on one sleeve bore from anti-freeze. Dealer said 'don't worry about it'.I told them 'I AM worried about it' so I had them to the P&S and of course bearings too. Cost was a few thousand more but now I have piece of mind and it runs a lot better to boot. Jim

 

[tim s]

Actually a bit of bearing wear will cause lower oil pressure, as well as a turbo seal will. It would be nice to know the true hours, to give you more knowledge of the possible wear.I would not be surprised to see some 'scuffed' pistons when you pull them out.The cam will be worn as well as the pump,,,the price of the O/H kit will be just the beginning, the crankshaft will most likely be good.

 

[tim s]

Fixerupper you did the right thing. When I work on them here I go all the way, my reputation is on the line when if I go half way,,,a month or so later after having the head of a piston will surly gauld, then you get to hear some one say "Tim just had that engine apart a little while back, what happened?"I have a sign in the office that says "Its easier to do a job right than to have to explain why you did,t"

 

[Ireland.29]

very hard to know the true hours! here is the original ad for the tractor which is still live over a year after we bought it, just in case any of you guys might have come across it before
http://www.equipmentlocator.com/asp/eDetails/JOHN+DEERE/eqID/679646/eID/1/loc/na-en/close/yes/
Untitled URL Link

 

[Ireland.29]

forgot to ask - can the cam / oil pump be done as an inframe?

 

[tim s]

Yes, but you will need to borrow a cam follower holding tool set, the followers need held up to let the cam come out,and even with the set it don't work out well, another reason I do most of mine out of frame,,that and I don't like to get oil dripped on me :>)

 

[larryanderson]

After seeing the pictures it looks like a decent old tractor.It has been repainted and it is obvious that is has some extra hours than it says.If you overhaul it do it right like Tim recomends or more than likely or you might not be happy.It most always pays to check them out on a dyno or get some history or have them inspected by an expert as it is usually cheap insurance compared to a problem.

 

[Ireland.29]

thanks Larry, yeah she is in good condition other than starting but it starts good if plugged in for 2 hours of with a sniff or two of ether. Im not in a rush to rebuild yet once it holds 40psi while working but Im leaning towards complete overhaul when I go in there. I would be happy to let the camshaft alone if it was ok though but will have to check out.
Any idea what the oil pressure should be?

 

[Tx Jim]

The oil pressure you stated[Oil pressure starts out around 45 and drops to 25 when very hot (at idle) but it holds over 40 all the time at 1700-1800rpm] is more than minimum spec's.

 

[Ireland.29]

thanks TX_JIM, thats got me thinking that with fresh
bearings the cam / gears might be ok but I guess I
wont know until I get in there. would you guys just
use the standard deere kit? ive seen some high
compression kits in tractorparts website

 

[tim s]

Keep in mind the cam and cam gears have very little to do with oil pressure...

 

[JDBert]

I'd look into a reliance "hyper" kit for it- little taller piston height- better compression and better starting. I wouldnt totally forget about the cam- you can loose a fair amount of oil pressure with worn cam bearings. I'd also get the head planed on the face and alson on the manifold side. get the valves checked- 404's have a habit of "tuliping" the valves into the seats and dropping compression further contributing to poor starting. I like to do them right when I do them- expensive- yes but i dont have to redo it!! Get the crank magnafluxed- ground or polished to size- new wrist pin bushings fitted to the new pins, get the rods sized and check the weights on them- get them all balanced to the lightest one, get the Block deck checked, new rod bolts, new head bolts. Go through the pump and injectors- get the turbo gone through, manifold planed. Seems like a lot and it adds up- but I never want to do a new motor and have a turbo puke parts through a it- or a pump or a injector fail or operate poorly and burn a hole down. check the gear on the cam- if the gear teeth still have a square edge on top its probably ok to run- if its sharp get a new cam. If you use the old cam and go with a new oil pump- make sure to switch the pump gear to the old one that matches the gear on your cam. If I reuse the cam I send it away to get ground as well as the lifters- especially if they are starting to flake. Oh and while your there- look at the clutch set up to- get the flywheel ground if you need to and install a new pilot bushing and clutch if you need to. I guess I look at it this way- my time is worth something- and while I'm "there" its going to be up to spec or new before it goes back together. If you put a $ amount on your time- it doesnt take long to burn up that figure to fix something while your there instead of taking it all back apart again.

 

[buickanddeere]

plugging any engine in to preheat before starting in cool weather is not a sin

 

[ben brown]

after i read through this post i decided i have been doing things all wrong. well probably not. if you had ask me to look at your tractor with a lot blow by i say it need a in frame at the least, and for few more dollar do a a out frame. i have the crank checked with 5000 hr on it head to machine shop put back to specs, replace sleeves piston, main bearing cam bearings rod bearing rod bolts, have cam checked. and replace injectors. now if it wasn't using a lot of oil and no blow by and under 5000 hrs on a jd i go with a un-haul main bearing rod bearings. i suggest that a jd get unhaul at under 5000 hrs old ih 414 466, 5000 and under and older allis 2500 hr. i suggest this from my own experience. now for engine parts i been using tom agr-diesel for about 15 years always got top quality parts and loads of help when needed, thy have reliance federal mogul parts and a good price. one other thing some one ex plane to me turbo kicks in or that turbo sure spools up i always though the turbo started turning the second exhaust hit the turbine

 

[LJD]

I'd pull the pan, pull some bearing caps and look at the condition of the bearings and journals. If there is journal wear, it will be easy to see. You can check clearances with Plastigauge to be sure. Nothing wrong with an in-frame if that's all that's needed. Now if it's already had 3-4 in-frames - who knows?

Some 4620s were dogs to start when cold since they were new. Some used just as much oil as your's when new also.

If you really want to tear into it this is what I'd do. I'd pull the bearings and inspect. If the journals are fine and bearings have normal wear- I put in new bearing shells. Cam and cam bearings are rarely a problem.

Two issues that really affect cold starting are the valve-depths in the cylinder head - and piston standout. Deere had problems with both in the 70s. And if some jerk ever did a standard auto-type valve job on it, the valves may be way too deep in the head. You cannot just grind the seals and reface the valves like you would on a car engine. They get too deep that way. The only good way to bring them up where they need to be is with valve-seat inserts.

As to the pistons? Deere corrected the problem year's ago with their new pistons. More standout and top piston ring is higher. I'm the sure has been done with aftermarket.

If you DO tear it apart, I suggest you get the big ends of the rods checked for roundness. On those engines with high hours they tend to get slightly ob-long. Easy process to correct them at the machine shop (shave and hone).

 

[Texasmark1]

I didn't follow the entire thread, but I totally agree that if cold startup is the only problem I certainly wouldn't go an overhaul if I had a reasonable starting alternative.

The problem I had with my Ford 3000D was that it was way far----too far gone. Previous owner had the intake manifold open to atmosphere and apparently used the tractor in a very dusty environment....funny thing, the bottom was intact, both main and rod cap bearings.

Mark

 

[4320diesel]

id get the head done and call it good untill the oil usage gets worse. my 71 4320 has 9900 hours on it (give or take 20 when the cable broke) and it got new injectors this spring, and still starts bad. i did noticed a few years ago i started it with the turbo unhooked and while cranking i got blue smoke out the intake manifold (leaky valves) so that is hurting starting. since its making 139 horse i can tell you someones been buggering with the pump output. if its been worked awfully hard with the pump turned up too high there is a risk of the pistons being harmed, but thats highly unlikely in a tractor engine designed to be run at a 1400*F EGT all day. but for now, try heavier oil and if you get excited about it taking ether to start when the sun goes behind a cloud (of if some ignorant bugger drives by with an icecream cone lol) then have the head checked.