2005 John Deere 4520 (Compact) Oil in Coolant

TurfgrassGuy · Sep 13, 2018

We have this tractor that has oil in the coolant. We have flushed the coolant thoroughly using flushing additives, etc several times, but after a day or two of use, the coolant becomes a gray-ish sludge. What is causing this, and what can we look for???? Oddly enough, none of the other oil levels (engine oil, hydro oil) are dropping noticeably. Any help is greatly, greatly appreciated!!

Einthewoods · Sep 13, 2018

It almost has to be a head gasket leaking. It doesn't take much engine oil to make the coolant look nasty. Not seeing changes in the oil level doesn't rule it out.

oldtimer 66 · Sep 13, 2018

It doesn't take very much oil in the coolant to turn it to a gray sludge as you say. I have a maintenance CD for my 4320 and it should be a similar type of engine/ 2.44 L JD Power Tech/ that you have in your tractor. The maintenance CD has several suggested causes. Faulty head gasket, faulty engine oil cooler, cylinder bore cracked, cylinder head and or block cracked. I would check the engine oil cooler first. It is located right behind the engine oil filter. Attached picture. I have had my off to replace the 2 coolant lines that were leaking. If you are going to remove the engine oil cooler purchase new rubber hoses and clamps. The one hose is a special molded hose. There is also a packing between the oil cooler and cylinder block which you would need new also. There are no instructions in the maintenance CD on how to check the engine oil cooler. If you wanted to check it you would need to make your own setup. Low pressure air thru the coolant lines and submerge the oil cooler in water and look for bubbles. It says that you need a special tool to remove the center nipple on the cooler. I used standard tools to remove it. The oil cooler is very fragile so handle it with care. Instructions call to torque the center nipple to 27 ft./lbs. on re-assembly. If the engine oil cooler is not the culprit I would suggest that you purchase the maintenance CD for your particular tractor and follow it thru to find the problem. If you feel that it is more that you would like to take on then I would suggest you contact your local JD dealer. There is also a possible bleed thru area in the forward end cover at the oil pump out put. That would deal with a water pump replacement, sealant and no FEC gasket, and stretch bolts in that area. That would be a last resort possibility. Later.

TurfgrassGuy · Sep 14, 2018

Thank you Gentlemen! At least I have some starting points to look for. I will order the maintenance CD this morning and get it on the way.

oldtimer 66 · Sep 14, 2018

Here is another idea on the possible leaking engine oil cooler. How about just by passing the cooler for the interim. You would need to re-clean the radiator and flush the system again. Run the tractor for a couple of hours doing some light work, no hard loading. If the coolant system stayed clean then more than likely that was your problem. Later.