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H3 OK, how bad...? (Oil Pressure)

Somethingbigandorange

Well-Known Member
Messages
53
Location
Arizona
2006 H3 155K miles 3.5L I5 w/5w-30 full synthetic. The oil pressure warning has been going off at idle when warmed up. Every time you say "oil pressure" the first thing out of people's mouths seems to be "oil pump", but why would it be OK cold and not warm? The timing kit was done at about 115K, I thought the pump got replaced with that but I could be mistaken (was not me). I can't quit thinking that the bearings/journals are shot and that I'm totally boned. Any thoughts on this?

ps Yes I tried a manual gauge, don't have a stinking adapter that threads properly so I am not sure how accurate the reading was but it dipped right down to about 10 when I got it on there. The previous sensor was bad (oil dripped out when I pulled the pigtail :whaa:) but a new one is in there now. I have a DMM, any way to test the new sensor?
 

Jeepwalker

Well-Known Member
Messages
857
Location
WI
Oil pressure is lower when warm b/c the oil is less viscious when warm. The lowest reading will usually be with a warm engine, in gear, ac on, with foot on the brake (lowest idle). A couple thoughts on oil pressure:

1) The new sensor might be slightly variant. I would think you can ohm the existing sensor out. Hopefully someone here may give the specs, or search the Colorado forums.

2) Double-check your mechanical gauge with another known-accurate mechanical gauge you have a high degree of confidence in. Be sure to bleed out all the air too from the oil line.

3) 10 psi "Might" still be within the minimum spec range. My hunch is that it is. I'm sure someone here who has the manuals can relay the minimum oil pressure. Still, if that does turn out to be the case (and that hasn't been determine) you'd rather not be at the dead minimum. Mfgrs often state a pretty low minimum which I think kind of covers their backside. That said, I had an engine which under worst case circumstances would go down to 4psi when hot. I went and got a sensor that had a 2psi minimum reading :giggle:

4) Did you say, you thought you had the oil pump replaced (or was it the water pump?)

5) Good possibility the bearings have worn ....but double check pressures first.

6) If the bearings ARE worn (and that hasn't been established), you could probably have the crank dropped and check the bearings and do a quickie and put in a new set of main bearings and a new pump ...for less than the price of a new set of tires. Yeah, it's not a fresh rebuild but I've known guys who've dropped in a set of new bearings and got plenty of good miles from an engine (my brother's done it a couple times).

But first, check pressures again with a 'good' mechanical gauge and the air is bled out of the line. If no improvement, Change the oil too, with a new filter, and see if it changes ...just in case there is possibly some filter pressure issues.
 
Last edited:

amrg

Well-Known Member
Messages
2,317
Location
Qatar
Had the same issue and solved it,

Try the following (easy to hard)

1. Check oil level and refill
2. Engine oil flush + New oil + filter
3. Check oil pressure connector/wiring
4. Replace oil pressure switch
5. Engine oil flush again or skip it and try seafoam treatment
6. What ended up working for me, pull engine out to replace oil pump but find out there is a clogged oil bypass valve inside the engine instead (it opens up when cold and supposed to close when oil goes above certain temp. If it doesnt, you end up with low oil pressure. Mine was gunked up)
7. Inspect engine bearings if you are at this stage!

I had this issue over 2 years, it would disappear when weather is cold. During spring and summer it would show up as i would have the a/c on and that gets the engine really warm. Revving the engine up used to make it go away. Ended up doing step 6&7 as the truck would end up ringing the oil alarm all the time when I idle and whenever rpms are below 1500.

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amrg

Well-Known Member
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2,317
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I forgot one step, before pulling the engine, check the oil pickup tube if its clogged, as it may reduce oil suction pressure. You may need to drop the front diff to access the oil pan.

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Somethingbigandorange

Well-Known Member
Messages
53
Location
Arizona
Thank you for all the input so far. I thought about the pickup but then I should have poor flow constantly. I understand the temperature affecting viscosity I just didn’t think that would be enough of a swing to cause this. Sorry I should have added that I did oil/filter already.

First i am going to the hardware store for a bolt to drill and tap for my own custom adapter for the pressure gauge. Then I will poke through the manual to see about the bypass (didn’t know about that and it is the exact symptoms). Once again thanks for all the great input!
 

scoreh3

Well-Known Member
Messages
1,024
Location
SoCal
Ok there was an old post on how to add an oil pressure gauge to and I5 motor. Here’s what I found for you.

I case you want to do the oil pressure gauge installed, I just did mine this winter. Not sure if my new status (low posts) on this forum will allow me to post links yet, but Ill post the descriptions.

Its not that hard to install an oil pressure gauge in the H3 I5, easier than I thought it would actually. There is a plug (with a torx or allen head) just above the oil filter on the front of the engine. That plug is threaded and it it is in the oil pressure channel. You just need a gauge and adapter. I got mine on Amazon

1. Plug: LS Engine Swap M16 1.5 Adapter to 1/8 NPT Oil Pressure Sensor LS1 LSX LS3 Gauge 551172

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

2. Gauge. You can use what you want, but this worked for me.
GlowShift Tinted 7 Color 100 PSI Oil Pressure Gauge Kit - Includes Electronic Sensor - Black Dial - Smoked Lens - For Car & Truck - 2-1/16" 52mm

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

3. A holder that fits the gauge.

All you have to do is remove the plug, install the adapter (with a little silicone), screw in the sensor that comes with the gauge into the adapter, route your wires, add power, and profit.

Its been working well for me for about 6 months. This picture is from another forum (so whoever made it you get credit) The sensor with the blue coiled wire is an aftermarket oil pressure sensor. the torx bolt is where the brass 90 degree elbow is. You do not need the elbow if you use the gauge i linked, its sits low enough in that it doesnt rub against anything.

attachment.php
 

Happy Hummer

Well-Known Member
Messages
1,300
Location
Wisconsin
01 Jeep Cherokee xj had chattering and crap pressure, sound, running and I ran a quart of marvel mystery oil for awhile and it cleaned out a lot of gunk. Very quiet now and running better. These 4l in line six are notorious for clogged Gund passage ways.
 

amrg

Well-Known Member
Messages
2,317
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I think the technical wording is Oil Relief Valve. I did the search then after the engine was pulled and the mechanic told me it was that.
Think it opens up when cold to reduce pressure (cold oil is thicker) and should close when hot, but in my case it was stuck open all the time

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Somethingbigandorange

Well-Known Member
Messages
53
Location
Arizona
Ordered an adapter off of Amazon. That oil pressure setup on the 'front' port is what I had set out to do when this *poop*show started, after I found out about the M16x2.00 threading on the factory port :gaah: I will kill the time until delivery of the adapter by running some stuff through the oil to try and clear anything out of the system. I have heard of the Marvel, another mechanic I know uses Amsoil, and I have a buddy who swears by ATF. Any other suggestions are welcome.

Thanks!:thumbs:
 

4speedfunk

Well-Known Member
Messages
4,212
Location
Tardville
Rislone! It works. It dissolves and loosens varnish and sludge from your motor. Do three oil changes in a row substituting one quart of Rislone at each oil change. You’ll notice your old filters will weigh twice the normal weight...full of goo!
It works best if you do an all-day road trip, as the heat and rpm seem to activate the detergent.
 
H

harveyspecter

Guest
Ok there was an old post on how to add an oil pressure gauge to and I5 motor. Here’s what I found for you.

I case you want to do the oilpressuregauge installed, I just did mine this winter. Not sure if my new status (low posts) on this forum will allow me to post links yet, but Ill post the descriptions.

Its not that hard to install an oilpressuregauge in the H3 I5, easier than I thought it would actually. There is a plug (with a torx or allen head) just above the oil filter on the front of the engine. That plug is threaded and it it is in the oilpressure channel. You just need a gauge and adapter. I got mine on Amazon

1. Plug: LS Engine Swap M16 1.5 Adapter to 1/8 NPT Oil Pressure Sensor LS1 LSX LS3 Gauge 551172

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

2. Gauge. You can use what you want, but this worked for me.
GlowShift Tinted 7 Color 100 PSI Oil Pressure Gauge Kit - Includes Electronic Sensor - Black Dial - Smoked Lens - For Car & Truck - 2-1/16" 52mm

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

3. A holder that fits the gauge.

All you have to do is remove the plug, install the adapter (with a little silicone), screw in the sensor that comes with the gauge into the adapter, route your wires, add power, and profit.

Its been working well for me for about 6 months. This picture is from another forum (so whoever made it you get credit) The sensor with the blue coiled wire is an aftermarket oil pressure sensor. the torx bolt is where the brass 90 degree elbow is. You do not need the elbow if you use the gauge i linked, its sits low enough in that it doesnt rub against anything.
Some benefits of synthetic oil are increased horsepower and torque from your engine. click here to read them more.
Your post is very detail. Newbie can easy to learn more experience.
 
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