No oil pressure

[kfrosty]

Just got my first M998 home. Installed new batterie and Iit started up smooth as silk. Engine sounded good and smooth just no oil pressure. No smoke or blow by that I see. Not sure it's a sensor or something else. Oil level is good. I hope to look at it tomorrow. Anybody else had this issue or have any suggestions as to things to look at?

 

[Dock Rocker]

I would put a mechanical gauge on it before I turned it over again.


Also dump the old oil and filter. You may want to check the pick up on the oil pump to.

 

[RustyM923]

Gauge, sensor, wire or ground issue. (Or really no oil pressure)

 

[kfrosty]

Thank you for the replies. I went back and checked my Gov Planet report as I wouldn't have bid what I did on this one if it didn't run and have oil pressure. The oil pressure in their test was close to 60 psi. So whatever it is had to happen between their test and now. I won it back in Oct but the EUC has taken this long. It was sitting at a tow yard but the batteries were toast so I would suspect nobody has been driving it in the interim. I'll file this with Gov Planet and do as guys suggest. Rocker, any tips on where/how to get a mechanical on it? (I'll google tonight but if you have any tips, I'd appreciate it.)

Thanks again.

 

[porkysplace]

Thank you for the replies. I went back and checked my Gov Planet report as I wouldn't have bid what I did on this one if it didn't run and have oil pressure. The oil pressure in their test was close to 60 psi. So whatever it is had to happen between their test and now. I won it back in Oct but the EUC has taken this long. It was sitting at a tow yard but the batteries were toast so I would suspect nobody has been driving it in the interim. I'll file this with Gov Planet and do as guys suggest. Rocker, any tips on where/how to get a mechanical on it? (I'll google tonight but if you have any tips, I'd appreciate it.)

Thanks again.

Pull the sender on the back of the motor and put a tee in and use both gauges.

 

[kfrosty]

Thanks Porkysplace,

I've been searching but can't find anything on this. Are their part numbers, sizing etc for the T, items to get? I'm hoping not to have to make multiple trips to Napa tomorrow in trying to troubleshoot this.

Thanks.

 

[porkysplace]

Thanks Porkysplace,

I've been searching but can't find anything on this. Are their part numbers, sizing etc for the T, items to get? I'm hoping not to have to make multiple trips to Napa tomorrow in trying to troubleshoot this.

Thanks.

I'm not positive on this but I think the factory sender is 1/8" NPT . A good parts store should be able to look it up . It wouldn't hurt for you to post the part numbers when you get done for future reference .

 

[Mike82ndABN]

My gauge says 0 sometimes, then i tap it real hard and it starts working again.

 

[porkysplace]

My gauge says 0 sometimes, then i tap it real hard and it starts working again.

And you trust the reading ?

 

[Mike82ndABN]

I trust it when it is working. It moves like an oil pressure gauge should, low at idle, higher at higher rpms. Sometimes it just drops to zero and it just needs a love tap.

 

[tage]

I trust it when it is working. It moves like an oil pressure gauge should, low at idle, higher at higher rpms. Sometimes it just drops to zero and it just needs a love tap.

haha!

 

[Retiredwarhorses]

This is common....like any M series gauge, test the gauge first...the procedure is in the TM.
usually the best way to get a cursory, is it a bad gauge or is not, is to cycle the ignition power on and off, does the gauge move at all to the initial start position for that gauge? Meaning, when there is no power, the gauge will fall flat to the left, power applied, the needle moves to a start position, again...this is a quick cursory check.
after that is to test the gauge...and that is simple on the HMMWV, they all pretty much work the same.
24volts of power, ground and the wire from the device being metered...bad grounds at the gauge are the no.1 cause, next up is the metered device connection is faulty, such as the OP sending unit on the back of the engine....take off the eng cover, remove the wire from the sender, make sure the connection is good. Down load the TM for TS section...there is a procedure from cradle to grave on the OP gauge.

 

[kfrosty]

So far it appears the tap to the oil gauge did the trick. Started, tapped it twice and it started working. Turned it off immediately and went back to zero. Change to start and it moves a little and after starting a couple more times, appears to be working now.

Thanks everyone.

 

[Retiredwarhorses]

To eye don't fix themselves....I had a truck do that, my first HMMWV as a matter of fact, sitting at a light and look down, bam! No OP! It was the sending unit connection....

 

[papakb]

I had a similar problem on a road trip up to Portland. About 200 miles from home my gauge started to read 0. The engine ran just like it always had with no additional clatter beyond the normal diesel noises. Pulled over and checked the oil level, it was fine. I bit the bullet and finished the ride up to Portland to the MVPA convention and bought the only 2 oil pressure gauges I could find. One read 15 psi with the engine running and the other read the correct pressure. Figure about 10 psi per thousand RPM after warmup.

My next step would have been to install a mechanical gauge on the back of the block with a T fitting as mentioned above and run the line out under the engine cover as a cross check. Most Napa stores should have the fittings but you should also be able to cobble up something at a Lowes, Home Depot, or Ace hardware.

Bottom line is the Faria gauges that AMG used aren't the best available. See if you can find a Stewart Warner gauge as a replacement, better quality. Something else to keep in mind is that if you start replacing things you want a 0-120 psi sender and gauge. A lot of the M series trucks only use a 60 psi sender and gauge and they won't read correctly if mixed.

Kurt
KG6KMJ

 

[hmmwv1]

i just got mine 2 weeks ago and mine did the same exact thing,i bought a new gauge and went to replace it and the ground wire on the back of the gauge was loose. i tightened it and it works great