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Cat 3126, Oil press. drops off from 50 psi. to 17 psi as it warms up

What is the Cat specs. for the oil press. in a 3126 Cat engine in a 938G loader

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According to their website the minimum oil pressure is 41 psi at idle. I'd suggest verifying the oil pressure with a manual gauge directly plumbed to the engine. If it is 17 psi when the engine is up to temp. then you may have issues with the bearings. You should take an oil sample and find out what the metal levels are in your oil to determine if the bearings are going

Posted on Nov 27, 2012


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Posted on Jan 02, 2017

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SOURCE: oil pressure guage drops after engine warms up

Slight pressure drop is likely from bearing wear. You could run a straight weight oil like sae 30, with a pint of marvel oil added.Don't use anything cheap though or it will add to the problem. The marvel oil will clean passageways just in case the pressure drop is the result of gunk in an oil galley.
You are still within the "safe margin"...minimum pressure at idle in gear, hot is 15psi (though I do not accept less than 20)
If pressure becomes steadily lower over time, either have the engine rebuilt or sell it. If you have an electric, not a mechanical gauge, you can put a mechanical one on there to verify actual pressure. Hope this helps you!!!

Posted on Apr 27, 2009

  • 167 Answers

SOURCE: cat 3126 using oil

If turbo charged it could be the center section oil seals.

Posted on Oct 27, 2009

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SOURCE: 3126 cat engine cranks, fires, runs for a ffew

If you have no codes you have lost fuel,Have you changed the fuel filter,and if you did was it full of fuel???

Posted on Feb 10, 2010

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SOURCE: 2008 tahoe oil pressure is at 20 psi on start up

If you hear any knocking or ticking when the pressure is reading low, do not drive it 'till you have it diagnosed.
If the engine isn't noisy, you may have a pressure sending unit going bad. I'd definitely put a mechanical gauge on there just to read the actual pressure. If it is low, you may have some debris on the pump pickup screen that is obstructing oil flow Normally if it wasn't as low as yours is, I'd use an additive to dissolve the gunk but at 5psi you may do damage before the screen is clean enough so I'd recommend you remove the pan. If the mechanical gauge reads normal, replace the sender and don't bother with the remainder of what I am going to say.
If you remove the pan and find nothing on the screen, check the engine bearings for wear. If worn the correct way to repair that is to remove the engine as debris often will remain in the internal passageways and return to damage anything you put in there. Pump replacement is only necessary when you have bearing damage. Pumps do not generally fail unless they are contaminated. It will not hurt to replace one if the screen is obstructed as some debris can enter the pump and lower its pressure capacity somewhat but if the screen isn't blocked, do not blame the pump for the low will be wasting your time and $ changing it.
Good luck...any further questions, just ask!

Posted on Mar 13, 2010

  • 90 Answers

SOURCE: 1999 Z-71 with high

I dont want to be the one to bring you bad news, but you most likly have engine wear. Bearing clearances, oil pump clearances all are getting out or tollarences. you can improve this by using 15/40 mptor oil , or heaver, but that is a patch. for a long shot change the oil presure sending unit or better yet use a mechanical gauge to verify the true pressure

Posted on Jun 11, 2011

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I dont want to be the one to bring you bad news, but you most likly have engine wear. Bearing clearances, oil pump clearances all are getting out or tollarences. you can improve this by using 15/40 mptor oil , or heaver, but that is a patch. for a long shot change the oil presure sending unit or better yet use a mechanical gauge to verify the true pressure

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Cat 3126 using oil

If turbo charged it could be the center section oil seals.

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