Low Oil Pressure

[pyro]

My oil gauge is reading steadily around 20ish as opposed to 40 (where it should be?). I don't know why the gauge itself would consistently read that low unless it really is running that low. What oil pressure are you guys running and what am i looking at; oil pump, lines, etc? Or is the truck just getting tired?

[AwesomeJ10]

There is a lot to be said about this.

It's probably a worn engine; cam bearings/main bearings/oil pump/etc.

The first thing to do is verify the oil pressure with a manual gauge to rule out the stock gauge just reading low. I bet the gauge is fine though.

You can put in new oil pump gears (costs about 15 bucks) which might help.

Get some 15w40 Rotella oil - that will help.

You can go 'all out' and remove the entire timing cover and do lots of mods to it to boost oil pressure. http://amcramblermarlin.1colony.com/photo2_1.html

My '88 AMC 360 in the waggy had about 140k miles and lost nearly all oil pressure. I did all the mods and they helped, but I eventually swapped in a good 401.

[pyro]

I may try the gears...how hard is the install? I currently have 10w-40 oil in it. ill pick up some 15w-40 if it'l help. hopefully the engine will last me awhile yet. no money for a swap any time soon.

[AwesomeJ10]

Installing new oil pump gears is pretty easy. Be sure to NOT use any rtv silicone - just use the gasket that comes with the gears. Some places like bulltear.com sell thinner gaskets which will boost pressure.

You should consider doing the mod outlined below. Drill out the restrictive hole. Requires removing the timing cover, which requires removing all the engine assecories including the harmonic balancer. This is pretty involved, but is very doable.

[Stuka]

The most common issue on AMC V8 is the timing cover gets gouged, which ultimately lets oil go past the gears. Which then results in low oil pressure.

When you pull the gears (easy to do) run a finger nail along the inside of the housing where the gears were. If there is deep scoring that's your problem.


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[WasBlue]

I'm having a similar issue, running ~30 psi cold, once warmed up I read 20ish unless idling in gear, then the gauge drops to zero, spiking occasionally. I have yet to check pressure with a mechanical gauge, and that sounds like a job for this weekend.

[The PIG Smith]

I installed a mid-plate on my oil pump that I purchased Bulltear.
It was cheap and easy to install.

[pyro]

for the record i have the 258...couldn't find much listed under that engine on bulltear

[Stuka]

for the record i have the 258...couldn't find much listed under that engine on bulltear

oooOOoooo...

The 258 is a whole different animal. Not sure what mine runs. I do not think the factory gage is correct. It says I have around 25 cold, and 12 when warm at idle. It does have 240+ thousand miles on it, so it may be correct. But it has very little valve train noise. And if it does blow up, it needs to be replaced anyway. So I am not overly concerned about it.

For you, I would try a mechanical gage, or a new electric gage.

[pyro]

yea i don't have much noise either and it seems to run fine. i'll try a mechanical gauge to test it for sure.

[carnuck]

Make sure your oil filter isn't orange

[lindel]

Make sure your oil filter isn't orange

The Fram curse...

[whsii]

If I did not have a manual gauge laying around, I first would replace the sending unit to the oil pressure gauge.

The electrical gauges / sending units system do wear out in time with debree collecting in the oil sending unit.

I have replaced several and have had a very good jump in oil pressure. (a manual gauge has shown this to be true in some instances.)

A late 60's, early 70's muscle car, needs a manual gauge. I dislike having oil piped inside of the cab, if I can avoid it. ( the newer gauges are better than...)

A manual gauge is the best medicine. I personally like the stock gauges, so I deal with them, but I have a manual gauge for testing...

Just my thoughts.

[carnuck]

Factory gauges are for amusement only. Any semblance between their readings and correct levels is purely coincidental!

[lindel]

Another thing that might help would be to look at the end plate. If it has gouges from the gears then smoothing it down with some sandpaper might net you an increase in pressure.

[CAPTSmith]

I agree with Lindel, had same problem with my 360ci in my '74 Javelin AMX. Also, a couple other oil mods for low oil pressure include run an oil line, in the lifter valley, from the oil galley to the 5th main bearing which is the weak point in the amc v8s. Also, an 8 qt Milodon oil pan with an external 8an hose from oil filter adapter to oil pan help me get 70-80 psi oil pressure. Below link as some details:

http://theamcforum.com/forum/engine-oil ... 16067.html

[WasBlue]

Make sure your oil filter isn't orange

When I was in parts sales I would do everything I could to deter my customers from those filters. All I use are Wix and I am very happy with them.

[carnuck]

Make sure your oil filter isn't orange

When I was in parts sales I would do everything I could to deter my customers from those filters. All I use are Wix and I am very happy with them.

Ditto. After having several blow up on me and others I swore off them (after swearing by them for years)

[pyro]

gonna pick up a new sending unit tomorrow...ill post up my findings.

[brielly]

Just replaced the sender on my 258. It used to read 0 at idle when hot. Now its around 30. Hopefully you'll have the same experience.