Overheating and low oil pressure?

KennyMillar

Member

Equipment
L1500DT Tractor with Loader
May 9, 2022
43
8
8
55
Central Scotland
My L1500DT was running for about 30 minutes at the weekend when I switched it off because the oil light was coming on at anything below a high idle.
When I switched it off I realised the water in the radiator was boiling. The fan belt is in good condition, and this engine (Z750) doesn't use a water pump.

The oil level was at the 'full' mark on the dipstick.

What should I suspect? Cooling system issue?, or oil pump, maybe?

It's also hard to start when hot, but starts easily when cold - could that be related?
 

GreensvilleJay

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Sounds like a 'thermosiphoning' style cooling system ( no pump ) so it is very important to have a clean rad inside and out ! They will last for several decades as long as maintained.

Plugged radiator ? For sure I'd clean the fins (spray hose water, from engine to outside) as well as drain rad and 'backflush'. do the same 'backflushing' of the engine block, when cold of course. Maybe ad one of the 'cleaners' to help remove 'stuff' in the cooling passages.

Hard to start when hot, sounds like engine beginning to seize up from being too hot. Hopefully no permanent damage.

Others with that specific model will know more.
 
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TheOldHokie

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My L1500DT was running for about 30 minutes at the weekend when I switched it off because the oil light was coming on at anything below a high idle.
When I switched it off I realised the water in the radiator was boiling. The fan belt is in good condition, and this engine (Z750) doesn't use a water pump.

The oil level was at the 'full' mark on the dipstick.

What should I suspect? Cooling system issue?, or oil pump, maybe?

It's also hard to start when hot, but starts easily when cold - could that be related?
Hard to diagnose with limited information.

Boiling in the block when the engine is shut off is not uncommon. Was the water boiling or the radiator venting with the engine running?

Low oil pressure at hot idle is a common symptom of worn bearings. I think that model is getting well up there in age so something to consider.

Dan
 
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KennyMillar

Member

Equipment
L1500DT Tractor with Loader
May 9, 2022
43
8
8
55
Central Scotland
Sounds like a 'thermosiphoning' style cooling system ( no pump ) so it is very important to have a clean rad inside and out ! They will last for several decades as long as maintained.

Plugged radiator ? For sure I'd clean the fins (spray hose water, from engine to outside) as well as drain rad and 'backflush'. do the same 'backflushing' of the engine block, when cold of course. Maybe ad one of the 'cleaners' to help remove 'stuff' in the cooling passages.

Hard to start when hot, sounds like engine beginning to seize up from being too hot. Hopefully no permanent damage.

Others with that specific model will know more.
Thanks for the reply! I will do the things you've suggested and make sure the rad and block are clear.
 

KennyMillar

Member

Equipment
L1500DT Tractor with Loader
May 9, 2022
43
8
8
55
Central Scotland
Hard to diagnose with limited information.

Boiling in the block when the engine is shut off is not uncommon. Was the water boiling or the radiator venting with the engine running?

Low oil pressure at hot idle is a common symptom of worn bearings. I think that model is getting well up there in age so something to consider.

Dan
Thanks Dan.
Yeah, I understand it's not easy to diagnose on a forum, so I appreciate your help.
This is my first tractor, and I only got it to help repair a long driveway from time to time, so I just need it to be good for occasional use. Having said that, I don't want to damage it beyond repair, or mis-treat it. So I appreciate the help of people like you on this forum to keep me right.
 

GeoHorn

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Kenny, another thing you might wish to consider is to stop using multi-grade oil if you are using such now.
Use a straght-weight oil such as SAE 40 and the low pressure at idle will improve.

Also, don’t be in a hurry to replace worn main bearings. If you can maintain 5 psi of oil pressure at hot idle…the engine will be just fine. That’s all it takes.

I ran a 4-cyl Ford at 5 psi for over 15 years and the next owner has been mowing with it now for over 4 years and it still only shows 5 psi at idle on an accurate gauge, using SAE 40 oil.

(SAE 50 is also available if you live in a warm climate)
 
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Russell King

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That engine may have a plug missing from the end of the camshaft.
Search camshaft plug missing or similar phrase to see if the symptoms are the same. One person fixed it by drilling through a cover instead of removing it for access to end of the camshaft at front of engine (I think)
 
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South 40

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Equipment
L1500DT, 750 Ford backhoe, 49 D4 Cat Repowered with 6.9L Diesel
Nov 12, 2012
168
52
28
Bloomsdale, Mo. USA
Hey Kenny,

First thing I would check or replace is the radiator cap, these things are pretty old, (I have one), also make sure the air intake screen in front of the radiator is clean and the fins are clear, (a bit of air and or water will work here just not real high pressure), that screen in front of the rad is really bad about getting plugged up, (very fine screen).

As for the oil pressure if the engine gets too hot it will thin the oil and cause a drop in pressure, especially if it is close to time for an oil/filter change, or you don't have the right grade of oil.

These engines are also bad about scale buildup inside the water jackets, I just took the top plate off mine and got some pics of the buildup, I will post them tomorrow after I bring my camera home.

Also check both hoses to make sure they are not collapsing they don't have springs inside them and the bottom hose has more than a 90 degree bend in it!

Make sure you run coolant and distilled water in it, I usually run a bit more than 50/50 on mine, I lean to the heavy side with the coolant.

As for the radiator, mine was so heavy I knew it needed cleaned out, so I took it to a shop and theses days they want more than I paid for a new one, I am replacing the rad, both hoses, & cap, I am also putting an electric fan on mine, but that is because of other mods I have made, (added PS).

I am going to flush my engine by itself before I connect the new hoses and rad.

The cooling system is pretty simple on these,(no water pump), but everything has to be kept up to par or it will overheat.

If this is the first time it has done this, it should be fine, these engines are tough and dependable.

I know you aren't in the states, so I don't know if you can but the same brand of oil I use in diesels, but I will check the brand name tomorrow for you, it is a heavy duty oil made for diesels, it is all I run in all mine.

Cheers
Samantha
 
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South 40

Active member

Equipment
L1500DT, 750 Ford backhoe, 49 D4 Cat Repowered with 6.9L Diesel
Nov 12, 2012
168
52
28
Bloomsdale, Mo. USA
Hey Kenny,

Here are a couple of pics showing the scale buildup inside my engine, they only show a small spot but you can get the idea.

P1000232.JPG
P1000235.JPG


Cheers
Samantha
 
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Daren Todd

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May 18, 2014
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low oil pressure is most likely the camshaft plug on the front of the engine. I had to do that repair on my old L1501.

I actually dropped the oil pan before pulling the front end apart and found the plug in the bottom of the oil pan.
 
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KennyMillar

Member

Equipment
L1500DT Tractor with Loader
May 9, 2022
43
8
8
55
Central Scotland
Thanks everyone!
I did an oil and filter change, and used a single weight oil as suggested.
The oil pressure light has gone back to normal now.
I think it has had the oil filter on it for decades - a genuine Kubota one with Japanese writing all over it and a real pig to get off!

Also found a hole/leak in the radiator :-( just a pin hole, but its annoying. Is it worth tyring a radiator sealer in it?