Hello All,

Hopefully one of you can shed some light on this situation.

The vehicle is a 1983 Dodge D250. I was able to remove the oil pressure relief valve cap as well as the spring but no luck with the valve itself. Don't know about other installations of the /6, but in this truck the motor mount is right next to the oil pump. This makes it impossible to look into the relief bore (combo of motor mount and cross member), and very difficult to insert any type of 'tool' to remove the valve.

I would like to be able to remove the valve, clean it and polish (I have Crocus Cloth). I was able to remove the spring and add a 1.5mm (0.060"), shim to boost pressure but would like to take the extra step and preform some TLC on the valve itself.

Looking forward to the feedback.

Thank you and take care,
K&Sons

I'd have put a manual pressure gauge on it and run it from dead cold to completely warmed up and seen what I have before I started shimming anything. Are you suspecting oil pressure issues?

Hello Volaredon,

Appreciate the quick reply.

We don't know the condition or mileage on the /6 as it replaced the original 318 at some point in the truck's life. My Dad estimated it is an '87 based on the pollution equipment on the engine. His assumption is higher mileage but decent condition. He is not really concerned about oil pressure as it sits at about 35 psi at idle (cold engine), based on a temporary mechanical gauge. The factory electric gauge sits in the middle of the range. The rocker arms are receiving a good supply of oil. Hence the rudimentary condition assessment. Still need to do a compression test.

Based on the oil pressure related posts on this forum, the consensus of opinion is to ensure the oil pressure relief valve receives some TLC. This includes ensuring the valve is not sticking in the bore (polishing), and shimming the spring to provide a minor boost in pressure or ensure the pressure is close to factory levels. Of course, this assumes there are currently issues with the valve and the spring has lost some of its tension due to age. Hence my question regarding 'how to remove the relief valve'.

Hope that helps explain the reason for the question.

Thanks and take care,
K&Sons

As far as judging an engine based on "amount of pollution crap" mounted, that's hard to do because of different amounts of it based on 49 state, Cali, hi altitude, etc.
But I'd bet that a "low altitude"49 state /6 anywhere from 84-87, maybe longer, probably weren't much different among them. Especially once subsequent owners strip them of originally equipped smog equipment as they age.

I know that my 85, slant 6 engine on the stand in my garage, has different cast in block markings than the older ones.
This one has similar to the small block ones with what looks to be a date code a little bit below the freeze plugs, on the starter side of the block, about even with cylinder 5 but it appears to be done in What I think is military date format-- day 1st, then month then year something like 29-5-85. And no stamping on block behind alternator. None of the numbers I see on it confirm to anything I've seen printed about ID'ing a particular slant 6 engine.
And being my truck was a 6-85 build it fits as it does with the portion of the PK number on the trans that is the date it was built.
I didn't see it while in the truck and covered with an inch of solid oil residue, starter in the way, etc. Not til it was out and power washed// though I admit, I wasn't particularly looking for this info.

It's cool that they swapped backwards from a 318 to a /6 in your truck, , but in a 3/4 ton, I'd have to wonder why. Usually most that swap engines in a 3/4 ton it's to go bigger. Even most I know with a 1/2 ton are quick to "swap to a 360" as even the 318 is like Rodney Dangerfield. Though my own 83 d250 and 318 I used to have, surprised alot of people seeing how much I towed and hauled with that truck.
My son just "bought that one back" from my cousin that I sold it to, in order to drop that 318 into a c body wagon he's getting going. Currently not sure what's going to become with the rolling remains yet.
I know that in some years a /6 could be had from the factory in a 3/4 ton. Sure your truck didn't come originally with a /6, even if not the exact one you're currently working on?
Being different trans bell housing, different mounts and radiator, and exhaust, at least vs a V8/ having to be different parts between the different engines,
I have to question how you know it was in fact swapped, as you say .. hood sticker? Hoods can be swapped too. What's the vin say?

Hello Volaredon,

Appreciate the detailed reply.

The truck was originally a 318 (5.2L), with a NP435 gearbox (bull low). The V8 was confirmed by the 8th digit in the VIN (T), the under hood sticker with all the options and the vacuum routing sticker on the driver's inner fender.

The truck was originally purchased by Agriculture Canada in Prince Edward Island and at some point in its life it was sold. I purchased it from a chap that was using it as a farm truck. By then the /6 had been installed, coupled to the NP435.

Thanks for the info on the date code numbers on the engine block. I had to use my digital inspection camera to find the number. Handy tool for something like this. Had to say it wasn't easy to read - hard to reach. On this engine it has 3 27 84, could see any dashes. This would lead me to believe it is March 27, 1984, the logic of this differs from yours. I would find it highly unusual for a US manufacturer to use day / month / year as this is common in SI (metric), countries or the military. Having said that, they may have changed the date code format in 1985 when your block was cast.

At least the mystery of the year of manufacture has been cleared up. Having said that, I'll have another look in a few days.

In the meantime, do you or anyone else have a tip on how to remove the oil pressure relief valve itself.

Appreciate all your insight!

Thank you and take care,
K&Sons

I think I used an awl, or a pick with a hook on the end..

https://www.slantsix.org/articles/oil-p ... valves.jpg

Hello Jase,

Thanks for the suggestion and the link. Will try the 'hook' tool although it is very difficult to get decent access due to the combination of the front cross member and motor mount. May have to resort to supporting the engine and remove the motor mount to make it a little easier.

It will be a few weeks before I can get back under the vehicle again. I'll update this post as soon as I have new information.

Thank you and take care,
K&Sons