Old topic: Oil

[FISCH]

Ok,

So have a fresh rebuilt engine. Don't know if the valves were hardened or not. Engine has about 1000 miles on it and I have been running Shell 30wt ND (non-detergent).

The oil pressure at idle is about 30 psi cold, and I typically run about 40 - 45 in 4th and running steady.

This past weekend I had been driving for over an hour and got about a 5 psi drop in pressure. The TM says minimal 15 psi at idle and 30 - 60 psi when running. So I don't think there was any loss of oil etc...

I think the reason why is the oil maybe started breaking down??? I don't know. I checked the level after driving an there did not appear to be any loss (old dipsticks... it is where it is by the eye ball).

So I am thinking of going to a heavier oil maybe 40? Looking for opinion. Not sure on the detergent-non-detergent thing.

Looked at the Shell Rotella 10W-30 thing, but just not sure. Of course there are all the varieties as well -- T1, T5, Triple Protection ect...

Right now the oil is crystal clear (fresh rebuild) so I really don't believe there are any dirt deposits etc... in the engine.

Buddy of mine indicates that detergent oil removes the zinc on the valves I thing Mike is the guru on this so if he could chime in it would be appreciated

Fisch

[Gordon_M]

Just run it for now and keep an eye on it. I know your engine is fresh, but it is generally acceptable on a well worn engine to have any oil pressure at all at idle, as long as it lifts well into double figures when it revs.

Oil problems tend to be limited - it either works or it doesn't. The classic mistake is to put detergent oil in an engine that has run for decades on non-detergent oil - it starts to loosen all the dirt and rubbish and washes it into galleys and passageways - normally means trouble.

If you had a fresh rebuild AND the oil system was cleaned out, you should be fine. If it continues to decline, change the filter and go for the heavier oil. If you still think it is a problem after that then pull the sump and check the main bearings, as those have the most effect on the oil pressure.

As for valves, your truck came with hardened exhaust valve seats as standard. If the machine shop did any inlet valve work they would have fitted hardened inlet valve seats but they are not critical items as these engines don't rev that high.

Drive it - watch the gauge.

[Ian Jamieson]

Hi Fitch,
on the basis that you have a fresh engine I suggest you go for a 15w-40 multigrade diesel engine oil (Rimula X or equivalent). These oils have a higher zinc value than gasoline engine oils and thus are better for flat plate tappets as used in the Dodge.

Given the 1000 miles since overhaul or refresh I suggest now is a good time to change the oil and filter. Make sure the engine is well up to operating temperature before you drain the oil.

To be honest 5psi drop over an hours running is really not worth worrying about. However a consistent 10-15 psi drop from cold to full running temp might bear investigation on a fresh engine.

Using a single viscosity oil will often give lower pressures when hot as the oil thins as the temp rises. The multigrade oil maintains a similar viscosity across a much wider temperature range and thus gives more consistent oil pressure.

Cheers

[jim lee]

I had a fresh rebuild 230 in my M37. Oil psi was 30-40ish. The builder said to "just run it, flatheads run at a lower pressure". So I did. 6k miles later, it spun #1 rod bearing. O' delight!

The builder said that at 6k miles it couldn't be his fault. When I pulled the engine down, I found the oil pressure valve was inserted backwards and a washer shimmed in there with it. Wrong wrong wrong.

Anyway, get another gauge, check the pressure and make sure you're happy with the results. There's actually a yoiuTube video all about the oiling systems of these motors and how to debug them. I don't have the link but you may want to have a look.

-jim lee

[FISCH]

Guys,

Thanks.

A few more details. First yup right at 1000 mi I changed the oil and filter. The guy who rebuilt it likes to run detergent oils so I wanted that out because that also removes zinc from the engine. I do use a lead additive, but will look at the multi-grade recommended.

I realize 5 psi drop over an hours straight running probably isn't alarming, but hey I like to pay attention to everything when I drive. For instance lacking an RPM gauge you can use the Oil Pressure Gage as it will go up as you rev etc ... when shifting gears etc...

It is just a bit disconcerting. I will look at maybe getting the multi-grade oil, but also wanted to consult the "brain trust" of the forum from those of you experienced operators.

I have been enjoying the car and am learning more as I go. Though I didn't handle a lot of the heavy lifting on the restoration, I did do the top and learned a lot on upholstery. I am looking forward to repacking the bearings at 6,000 mi (or is it 3,000 - have to check the TM).

I do need to service the shocks - never did knee shocks before so this should be interesting.

Other than the aforementioned, I have been taking my vehicle on parades, car shows and cruise-ins.. get lots of questions and even a few awards.

Part of the fun of all of this is the tinkering - repairing, and learning.

[Kaegi]

the diesel oils in the US now do not have the high zinc content anymore. if you go to napa they sell a performance oil that has zinc in it for flat tappet engines. they call it a racing oil. pressure will always drop a bit when warm because the oil thins out not because its breaking down. your pressure does seem too low to me for a new engine. should be 20 plus at idle and 50 to 60 at high rpms. maybe check the relief valve set up and if that is all good then maybe a better oil pump.