Oil plugs on side of engine block

[40desoto]

I noticed 4 oil plugs one one side of my 230 engine and Im using one as a return for the remote oild filter.  My questions are;

What are the purpose of the other 3 oil plugs? 

Im installing an aftermarket oil pressure guage what would be the best pressure souce for the guage? Which of the 3 remaining plugs can I use assuming you can use one to install the guage.

 

 

[greg g]

If the oil is going in at engine pressure how can it exit at engine pressure? If you connect both lines of the remote filter to the ports on the side of the block, they are getting the same pressure so essentially you are flowing no oil through your filter. The Oil return line line from the original style filter goes to a port located adjacent to the dip stick. The gauce can be picked up from any one of then not in use, as the hole galley should be pressurized the sam along its length.

[Lumpy]

I would guess that those holes were drilled after the block was cast, in order to blow the sand and slag or whatever out of the oil passages. Then they were threaded and plugged. Kind of like the core plugs, which are often mistaken, and called "freeze plugs".

 

But...I could be wrong! Just a guess.

 

I think Greg is right...again...there is probably no oil circulating through your filter.

 

ken.

[TodFitch]

I would guess that those holes were drilled after the block was cast, in order to blow the sand and slag or whatever out of the oil passages. Then they were threaded and plugged. Kind of like the core plugs, which are often mistaken, and called "freeze plugs".

 

But...I could be wrong! Just a guess.

 

I think Greg is right...again...there is probably no oil circulating through your filter.

 

ken.

I think you'll find those pipe threaded plugs line up with the main bearings and were the access for drilling the oil feed lines to the bearings. Threaded plugs as they need to hold back 60 to 100 psi oil while the water jacket plugs have little or no pressure on them -- unless you rev the engine when cold and the thermostat hasn't yet opened (ask me how I know).

[40desoto]

If the oil is going in at engine pressure how can it exit at engine pressure? If you connect both lines of the remote filter to the ports on the side of the block, they are getting the same pressure so essentially you are flowing no oil through your filter. The Oil return line line from the original style filter goes to a port located adjacent to the dip stick. The gauce can be picked up from any one of then not in use, as the hole galley should be pressurized the sam along its length.

Greg your right  I do have it installed right I just described it wrong..  my return does go to the correct place.

[Lumpy]

Now Tod is right...and that's not unusual for an engine to have plugs where some kind of drilling has to be done for various reasons. I never looked at those plugs with that in mind before. 

 

Just as an aside, revving a cold engine can also lead to broken rings, or broken ring lands on the pistons, as the pistons are rocking around quite a bit before they expand...so always a good thing not to do besides popping the core plugs.

 

40, glad to hear your filter oil is circulating!

 

ken.

[40desoto]

Im almost sure these are factory plugs.  Not that Ive seen many but all 4 blocks ranging from 218, 230, 251 all had these plugs alligned with the oil circulation chambers.  What interested me was that on my 251 Chrystler block the plug where the factory oil pressure guage connected sat a tad bit lower and was a larger hole than the other three that where just plugged. That made me wonder if that would read a different pressure reading tha the rest.

[Lumpy]

Good question, as I've wondered if the readings would be different depending on location.

 

ken.

[greg g]

the factory 251 likely had the full mopar style flow filter system, rather than the 218/230 bypass system. As such it was mounted and plumbed differently than the bypass system. If you are attaching the remote filter to the passageway you are still maintaining the bypass system, just attaching the filter and mount to a different place. The type of filter element really won't make a lot of difference unless the filter itself has an internal bypass and or pressure valve.

Edited March 7, 2014 by greg g

[40desoto]

Since I have both the 251 and the 218/230 block out of the cars I will tak some pictures of each and post.

 

The 251 I have did not have the full flow system. 

[Don Coatney]

the factory 251 likely had the full mopar style flow filter system, .

Not all long block Desoto and or Crashler engine blocks have provisions for full flow oil filtering. I have not yet found the reason for this. It does not appear to be year specific not brand specific. I do know that the filter housing is shared with the early Hemi engines but this housing I believe was in use on the flathead engines as early as 1946. Hopefully someone in the know will chime in.

[40desoto]

Note the larger Oil pressure guage port on the 251 Engine.  Why I asked the question if which port for oil pressure reading was ideal.

 

[Don Coatney]

My 251 block does not have that larger port in the oil galley. Typically the oil pressure gauge is connected to the threaded hole at the rear of the engine oil galley. In theory oil pressure is based on pump output verses resistance. The more resistance (as in well fit bearings etc.) the higher the oil pressure. With worn bearings the lower the oil pressure. Any port along the oil galley should show the same oil pressure gauge reading. So I don't believe there was any advantage to using the larger port for a gauge connection. As to why that port is larger is anyone's guess. Original threads could have been damaged and a larger hole drilled and tapped to make repairs.

[TodFitch]

. . .. As to why that port is larger is anyone's guess. . .

My guess is that the oil pressure gauge line and the oil filter supply were both taken off that port so a relatively large T fitting or equivalent was used there.

[Lumpy]

And I don't suppose (I think that's an oxymoron) it matters if you get a reading one or two pounds off, compared to any other port. After driving the car, one becomes familiar with what is normal pressure for that engine, and that's what really matters. With all of the variables that determine pressure, I'm sure no two engines read the same no matter which port you use.

 

ken