77 245DT oil pressure help

[Trailfarmer]

Some-time lurker, new member.
Tried lighter weight oil during recent oil\filter change on my 77 245DT with about 1500hrs. Now after warming up oil light comes on when tractor is at idle. Revving engine makes light go off. According to dip stick oil level is ok. No problems like this before the change.

Need heavier weight oil? Saw a comment in another thread that lighter oil may not be best choice for older engines.
Oil pump going bad?
Oil sensor going bad?

I am reasonably competent at working on my own stuff but don't have any pressure testing equipment, etc

Local dealer is $75 hr (+ transport) so I'm hoping you folks can help me figure this one out at home

 

[Trailfarmer]

Some-time lurker, new member.
Tried lighter weight oil during recent oil\filter change on my 77 245DT with about 1500hrs. Now after warming up oil light comes on when tractor is at idle. Revving engine makes light go off. According to dip stick oil level is ok. No problems like this before the change.

Need heavier weight oil? Saw a comment in another thread that lighter oil may not be best choice for older engines.
Oil pump going bad?
Oil sensor going bad?

I am reasonably competent at working on my own stuff but don't have any pressure testing equipment, etc

Local dealer is $75 hr (+ transport) so I'm hoping you folks can help me figure this one out at home

 

[BigBoyToys]

What were you using and what weight oil did you put in?
In general a lighter weight oil will result in lower oil pressure.

 

[Trailfarmer]

I switched from 10W30 to 15W40 and it is the kind for diesels.
Changed it about a month ago, weather was 60s--80s.
Been busy with some many other projects, but need to get it figured out so I can get some fall\winter chores done.

Would a continuity tester or something similar tell me if the oil sensor is bad?

 

[varmint]

Greetings, Trailfarmer! I lived in Greater Lafayette (and W. Lafayette) for most of my first 37 years.

That said, go to an auto parts store, and buy a cheap mechanical oil pressure gauge. Most should come with various adaptors. I installed one on my old '87 B8200 Kubota quite easily, by installing a brass tee (male/female/male if I remember) where the oil pressure sender on the side of the engine block screwed in, taking the new gauge line off from the tee and screwing the idiot light sender back on the other side of the new tee. That way, you will see what the pressure actually is at various RPMs. And, 15w40 is heavier, not lighter, than the 10w30 you say your started with. That would worry me!

 

[repete]

Perhaps the heavier oil is unable to push through the filter when cold and therefor lower pressures on the downstream side of the filter.

 

[varmint]

15w40 isn't exactly 50w, and wouldn't the filter's bypass let oil thru? Don't think this is figured out yet...

 

[lakeridge]

The camshaft has a machining plug on the end of the shaft. This plug can fall out and creating a big enough within the lub. system that the pump cannot keep up at idle.
When you throttle the engine up the pump flow increases to compensate for the leak. I ran into this problem many years ago. Plug is pressed into the hole and simply feel out.

 

[BigBoyToys]

You said you changed your oil, how long has it been since the filter has been changed?

The bypass valve in the filter will open for a few reasons...
1. The filter is clogged/dirty.
2. The oil is too "thick" at cold temps.
3. If you were to accelerate hard and build up oil pressure too quickly. (Unlikely in a tractor).

The bypass valve opens in these conditions so the engine isn't starved of oil. "Unfiltered" oil is better than "NO" oil!

Most tractor manufactures seem to recommend 10W30...try going back to it.

 

[MossRoad]

Duplicate threads merged...

 

[Trailfarmer]

Just wanted to post an update...thanks to those who have given advice...

Have been swamped with other commitments and on the road quite a bit the last week or so haven't had a chance to "play" with the tractor. Spent about 3 hours today mowing and blowing after our big "leaf rainstorm" on Saturday.

I did use a new filter during the oil change, so I think I'm ok there. (In my experience it never hurts to check the obvious. Can't tell you how many times I've seen " junk dirt bikes that won't start" with empty gas tanks...)

Plan to look at my owner's manual tonight and see what it takes to get to the cam and possibly pursue that direction.

Depending upon results will check auto parts store for pressure test kit in next couple of days.

I made the decision of going to the different weight oil after reading an older, fairly lengthy thread about oil weight on this site. There is a part of me that wonders if changing weight caused the issue but I kind of hate to spend the money to change the oil back and find out it's not the problem.

I'm still open to ideas and help. I'll update in a couple of days with hopefully good news.

 

[Trailfarmer]

Another update.....started tractor today and had no problems with oil sensor light coming on. Used tractor a bit and let it return to idle several times--still no oil sensor light. Perplexed on what is going on.

Plan to pick up oil pressure gage after work Tues. Hate to spend time and money if "nothing is wrong" but hate not to if something is wrong....

Can't find any "obvious" things amiss. Temp and work conditions today about same as the day the oil sensor light kept coming on at idle.....

 

[D2Cat]

Trailfarmer you say, "Hate to spend time and money if "nothing is wrong"."

I'd say send a few dollars for the mechanical gauge with the idea of mounting it somewhere out of the way and have it as a constant double check. Be secure in knowing what you oil pressure is, not only that a light is on indicating your pressure is less then 7#!!!!

 

[varmint]

With a '77 tractor, you might benefit from adding more gauges to watch its operation. I added a trio to my old B8200, cost me under $20 (and the time to mess with everything) but I liked having the gauges, just to keep an eye on the engine systems. Oil pressure, coolant temp. and volts.