990a crankcase pressure

[bel]

went through that with pickup head full overhaul sent head in resurfaced reseated valves not new ones. on first start up valve head broke off busted piston and cracked block not a good short cut to take

[bel]

im guessing before getting overhaul kit I need to mike crank and rod jernals. I rebuilt this engine about 25 years ago think I was able to put rear crank seal in.either that or I didn't replace it. you can put it in without separating tractor right just doing in frame

[ollek]

No you can not get to the crankshaft rear oil seal with the engine in the frame. You have to remove the clutch and the flywheel before doing the crank rear seal and this involves splitting of the tractor.

[bel]

ok men
found no 1 rod bearing wiped out didn't get into rod but bearing is chewed up.worse than that crank on that journal is scored. so its split the tractor and replace crank and clutch while im in there and complete overhaul.just cost verses what tractor is worth now.thinking of giving up.need some input

[bel]

also with these problems timing gears are off. rotated crankshaft gears have one punch mark on one side,two punch marks on other side couldn't get them to line up on cam or injector pump no where close. still doesn't explain crank case pressure.

[bedwards1966]

I'm not the person to help on the timing, except to say that you might find that the timing marks only line up once in a certain number of revolutions which if you aren't aware of can lead to a lot of grief.

It may be a lot of work on an old tractor, but the way I look at it is this:
1. They are brilliant machines which still perform very well, as they're no longer made it's sometimes necessary to put some work into them which is well worth it in the long run. Usually works out cheaper than trying to replace it with something modern which you soon discover is not built very well.

2. Make a good job of the engine then keep it maintained with fresh oil and filters and you can expect not to put a spanner on it for the next 40/50 years. Take the cost of a rebuild against how long it'll last and the numbers are quite favourable.

[joeproctor]

can you post some pictures so that we can see what you have damaged and can offer advice accordingly.

[bel]

joeproctor,
I will see what I can do about pics haven't posted pics on here before.think im going ahead with overhaul was hoping for a in frame but crankshaft is going to have to be turned.last time I adjusted clutch it was out of adjustment so planning on changing it too.ill try to get pics probably have to get my son to put them on here

[db2d]

There is not a problem with the timing gears. Align the marks after refitting crank.

[cobbadog]

I feel it is better to keep the one you know all about as to buying another one that you will possibly have to start from scratch to find its real condition.
When doing our 30C engine I put #1 piston on TDC and marked the timing gears using a centre punch as the single dot on one gear never aligned with the dots on the second gear. From memory in the manual it described the method of setting your cam timing to the crank and right at the end of the description it then said but if they do not align up you may have a different gear in place. I know that when I inspected the gears the small idle gear that went across to the governor was damaged and lead me to believe that a tooth had been chewed up and then the cam gear was replaced using the right size gear but from another engine and did not allow the dots to align. So my punch marks was what I used and it worked a treat.

[db2d]

The timing gear arrangement on a 990 Diesel is different to what is used on a 30C. Remarking the gears is not necessary and in my opinion would introduce confusion.

[bel]

CrankCase1.pdf

4 photos in one

(125.69 KiB) Downloaded 93 times

Here are some pics maybe they will help

[bel]

ok men
the crankshaft journal is scored and is going to have to be turned. the timing marks don't line up anytime but it was running when I started tearing it apart so it has to be close.Ollek is right ive got to get a manuel. if you look at pics of piston heads see the scuff marks on side what do you think caused that? its only on 2 pistons. number 1 rod bearing being out is why piston had slight valve mark on piston but was only in carbon on top of piston didn't hit metal. date code on plate is 9/50 which is early model im assuming it has filter on top of rear end and its a AD4/47.ive never split one before but have everything to do it in a shop.really want to get this back in shape but hoping I don't run into anything else.advice would be appreciated

[bel]

still don't know why it had enough crankcase pressure to blow dipstick out 30 yards from tractor sounded like a shotgun blast

[ollek]

Piston blow bye in combination with a completely or partly blocked crank case breather (can be ice, dirt or kinked breather pipe), will blow out the dip stick or the oil filler cap. It will also lead to a oil leak from the rear crankshaft oil seal into the clutch housing. There is nothing strange about this.