I need my truck, and I don't know whats up...

[Spitfire1975]

Truck started running HIGH oil pressure today and I don't know where to start fixing it.

1986 2.9 2x4 ~170,000 miles

Idles normal, taps out high under load, drops to normal under idle.

Seems to be running great.

Oil looks clean and is not full, if anything 1/2 quart low.

What can cause this? Can I drive it assuming I have a bad sending unit?

If not, what the heck do I need to start looking at? I need the truck to get to school tomorrow.

 

[Nhaz]

My first guess would be a old dash gauge or alternator, If its bouncing to high at idle. That's when the alternator is most likely to be putting out Pulsating DC which generally shows up in pulsing lights and gauges at low rpm. Check voltage at idle with a analog meter. you might not see it on a digital one.

 

[jhammel85]

My first guess would be a old dash gauge or alternator, If its bouncing to high at idle. That's when the alternator is most likely to be putting out Pulsating DC which generally shows up in pulsing lights and gauges at low rpm. Check voltage at idle with a analog meter. you might not see it on a digital one.

Any other gauges acting weird like that? Because he's dead on...Thats a good point.

If not, I would imagine that most likely that sending unit is on the fritz. Next possibly the gauge.

 

[fyre82]

You can check the gauge operation by grounding it out and have someone look to see if it goes all the way up, hesitates or doesn't move correctly. They are notoriously bad for accuracy anyway, but senders do go bad.

 

[Spitfire1975]

It pegs out high when driving under load, like going up a hill. If coasting Down the hill in neutral, it will return to the normal position. Put it back under load and it will peg out high again and stay there until the load is removed. Not a quick movement of the needle either. It will take about a minute for it to go from normal to high. The Starter solenoid/switch is acting fritzy, again (for the third time in 1000 miles). Could that affect the electrical system in such a way the gauges will go screwy?

No other gauges are acting weird.

I am assuming all this means there is nothing mechanical wrong and I don't have to worry about blowing up the truck.

 

[adsm08]

I'd assume an electrical issue as well. I'd start with the alternator check, and move from there. It may also be a screwy wire that only gets stretched under load.

 

[feellnfroggy]

When underload the pump works harder if Im not mistaken, Alland will post and corect me if Im wrong but when bearings go bad, you can see a higher pressure or when little tubes get clogged or anything similar. Your ears will be your best friend here.

 

[ForOffRoadDriving]

i would say buy an inexpensive gauge at the parts store (around $25) and hook it up temporarily so that you can see it while driving and make your diagnosis that way. these factory gauges are so far from accurate its ridiculous.

 

[Spitfire1975]

Ok. Will replace the screwy starter switch, see if that makes a difference and if it doesn't I will buy the oil pressure gauge.

 

[Spitfire1975]

Starter switch did not help. Will be getting either a new pressure sending unit or gauge here pretty soon.

 

[Duane867]

Buy a new after market gauge. Screw the factory gauge and sending unit.
They are garbage. Its easy to install and you will know immediately if you really have high pressure or not.

Now on the mechanical side of things... 2.9's have HORRIBLY FLAWED oiling via two cam bearings supplying oil to the entire valve train.
They wear just a hair and the lubrication is seriously hindered. Combine that with poor cooling and they all eventually have a clatter from hell.
Not that 2.9's can't be made into a good engine OR that some out there have been or are not great engines currently. Thats just been my experience with them and most of my friends.

 

[BRUTUS_T_HOG]

Truck started running HIGH oil pressure today and I don't know where to start fixing it.

1986 2.9 2x4 ~170,000 miles

Idles normal, taps out high under load, drops to normal under idle.

Seems to be running great.

Oil looks clean and is not full, if anything 1/2 quart low.

What can cause this? Can I drive it assuming I have a bad sending unit?

If not, what the heck do I need to start looking at? I need the truck to get to school tomorrow.

you need to hook up a mechanical gauge to verify you actually have a problem.

i've had my gauge do this and it was a clogged oil filter (fram, coincidence? dunno)

but what tipped me off to that was the fact that the gauge would slowly climb then release to normal over and over again. switched to motorcraft filters and never had the same thing happen

 

[Spitfire1975]

you need to hook up a mechanical gauge to verify you actually have a problem.

i've had my gauge do this and it was a clogged oil filter (fram, coincidence? dunno)

but what tipped me off to that was the fact that the gauge would slowly climb then release to normal over and over again. switched to motorcraft filters and never had the same thing happen

I was wondering if it might be the filter. I sea-foamed the engine before moving (ran it for 200 miles and changed oil/filter again) and was thinking maybe the long run clogged up the filter with sludge. It's not a Fram. This filter is the Motorcraft from Wal-mart. I think Motorcraft is Motorcraft?

The truck is sitting right now. Bought an Escape and will be checking out the truck in between classes when I have a few moments.