Oil in radiator L1501DT

Kubota 101

New member

Equipment
L1501DT, Bucket loader, back blade
Jun 19, 2018
1
0
0
Trout lake, WA
Hello. I have a grey market L1501DT. 809 hrs. Bought used just under 800 hrs.
Used a number of times for 1.5 + hr work sessions plowing snow, moving dirt, manure etc.

This spring - first time out ( not used over winter - ran fine in fall). Oil was noticed on tractor and ground. Stopped work. Upon inspection - oil was in radiator. With radiator removed, we pressure tested cooling system and it held 3-5 seconds before slowly leaking out.

Since then:
1) Got parts manual for L185
2) Replaced head gasket, water jacket gasket, oil filter
3) cleaned radiAtor, parts, gasket surfaces etc
4) head was air pressure tested at machine shop
5) Head and radiAtor carefully re installed, proper torque for bolts etc


On initial inspection we suspected the head gasket and the o ring was slightly compromised at the oil port/ stud.

First 15-20 min test run was fine. Next day worked 1+ hr to get engine hot and flush radiator. Oil light began flickering while in use after a while. Checked oil - oil was out of engine - into radiator again.

Note:Cooling system held pressure after engine stopped and still hot.

Next we plan to remove front cover and inspect frost plugs - I AM SEEKING ADVICE/SUGGESTIONS - what to look for, what to inspect etc. Thank you
 
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rademamj

New member
Apr 9, 2017
43
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0
Waco, Texas, USA
Not sure exactly the specific cause without a detailed investigation. You do appear to have done all the required work to diagnose and prevent oil in the radiator. Especially the head was air pressure checked for cracks. After all that engine work, are you seeing a few cups of oil or just a sheen of oil in radiator.

You need to check for a hairline crack in the head again. One may have been missed. Apparently, as the engine head heats up, the crack expands and opens in size. Won't see it on a cold head. This crack most likely is located between the oil and coolant lines....thus connecting the two types of fluids. Since the oil line is always under higher pressure than a water line, the crack only allows oil to be pumped under pressure in one direction....into the water lines. The oil eventually is collecting in the radiator at the top and can be seen visually when opening the cap.

Need to check for this hairline crack in the head. Ultimately, the fix or solution is going to require a head replacement.

Question: Was the tractor ever overheated (even for a short time)......because that is the primary cause of most head cracks in tractors.

The good news is, no water coolant will ever go through the crack and contaminate your oil....due to pressure differential. I have used a tractor for 6 months while waiting on a new head to arrive. Every week I was adding oil to the engine and draining the radiator (coolant + oil) until my new engine head was delivered. Indeed the new head solved the problem.

Sent from my SM-G930V using Tapatalk
 
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North Idaho Wolfman

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Lifetime Member

Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
33,389
8,703
113
Sandpoint, ID
It's not a frost plug, it has to be a oil pressure side leak, since you've addressed the head and head O-ring, next best guess is O-rings on the gear case.