4630 compresson questions

MHG

Member
Hi everybody. Need some advice on a 201 engine. 1st a little history. Tractor has 6000+ hrs. Since day 1 has had a lot of blow by, will run hot when pushed hard in hot weather and oil will turn black in a few hrs. Oil and filter changed every 100 hrs and always had conditioner in coolant. Last 2-3 yrs will burn a quart between changes. Will start fine when cold but is very hard starting when hot. Ran a compression test today with a good strong battery. #1&2 300 psi. #3 280. Add a little oil #1&2 jumped to 340 psi. #3 320. Haven't done leak down test yet. Don't know what specs are. Whats the verdict, are those numbers too low? Thanks in advance for the help. MHG
 
350-375 is more typical. That said, your numbers don't jive with the fact that you said it starts fine cold. How cold is cold?

Hard start when hot points more to an injection pump issue.
 
Hard starting cold usually due to low compression heat. Hard starting hot is usually worn injection pump hydraulic head on rotary pumps, like Bern said, or worn plungers
if inline pump. Could also be too slow cranking speed, battery, cable, or starter trouble.
 
(quoted from post at 05:31:44 12/31/20) Hard starting cold usually due to low compression heat. Hard starting hot is usually worn injection pump hydraulic head on rotary pumps, like Bern said, or worn plungers
if inline pump. Could also be too slow cranking speed, battery, cable, or starter trouble.
Bern and Dieseltech, It's the rotary pump, cranking speed is good. Last 10 days been using it to feed and lights right up without glowing at 25-30 degrees F. Bern, I'm gonna do a leak down test next. But maybe compression isn't that bad? Am I looking for trouble? Thanks for the help guys. MHG
 
I agree with DieselTech, probably pump issue.

If it starts good cold, engine parts probably up to snuff.
 

With 6000 hrs it's going to have some leakage, but you'r looking for trouble in the wrong place.
If it cold starts like you say compression isn't the issue, sounds like a fuel issue, MIL's 5600 does the same thing at times with 6300 hrs, injection pump needs rebuilt.
I've learned over the years to pay little attention to blow by, weather conditions and engine temps will have big effects on what blow by looks like, one day it's hardly noticeable, next day the steam vapors are so bad I check to make sure the tractor isn't on fire.
My rule of thumb is if it starts good cold, runs good and uses less than a couple of qrts between 200 hr oil changes it's a good engine.

As for the over heating issue clean the radiator and I mean clean it good, had a over heating issue with my 6610, blew the radiator out, washed out out, still ran hot. Finally pulled the radiator to have it flow checked and possibly recored, once out in the light I could see 60% of the fins were blocked, about 30 minutes of cleaning with a pressure washer got in good and clean stopping the over heating issue. If that doesn't fix it thermostat then water pump in that order would be next.
 
Thanks for the help everybody. Sounds like injection pump may be the biggest problem. Will take it into shop next week. Will take in radiator also. MHG
 
Don't overlook a bad or loose fan belt. With the engine off you ought to be able to turn the engine over....somewhat, just by grasping one of the blades.
 
With your maintenance being up to snuff and all, you might dump a 16 oz can of Sea Foam in the crankcase, engine good and hot like you just finished plowing with it and let it idle for half an hour before you shut it down and drain the oil......maybe do it 2 oil changes in a row, or more if necessary.

With the drain plug out, stick your finger in the hole and rub the bottom of the oil pan. If you find sludge, you need to get that out and then you can have clean oil for a spell after you change it.

Couple of years ago I bought an '88 3910 with 900 actual hrs. In short, it had about a ⅜" layer of sludge. Couple of SF in the oil as I mentioned and it was all gone and oil stayed clean. May up your compression too.....loosen up stuck rings and let them expand like they are supposed to do....SF loosened up my '63 Ford 2000D with about 3700 hrs and no wrenches on the engine proper ever. Started up in the winter with no starting aid in 5 to 10 seconds on the starter but had the blue smoke pretty bad. Did it to that baby and hardly any smoke at all now.
 

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.

Back
Top