3.9L timing chain tensioner on '89 LA 360: Drill for far-left oil hole or not?

[cudak888]

I've found conflicting information in regards to this oil feed hole via a forum/Google search, mainly as most factory blocks appear to have sealed welch plugs installed. Not the case here.

My '89 LA 360 (360-3, roller cam) has a factory (this motor has never been apart until now) pinhole of an oil feed coming through the left side, and a hole to match on the camshaft thrust plate:

None of the bolts have a similar pinhole drilling through the center, so I assume this is Chrysler's supplement the timing chain oiling tab and whatever happens to dribble out of the camshaft thrust bearing.

And here's the 3.9 thrust plate/tensioner:

Unlike the original, this plate does not have that area drilled. So my question is to those who've worked with this combination before: Drill the new tensioner/thrust plate, or leave it capped?

-Kurt

 

[RustyRatRod]

Drill the bolt all the way through that is going in the upper hole on the passenger's side of the engine.

 

[cudak888]

Taking no chances. If the factory drilled a pinhole into the welch plug, the hole is supposed to be there. Drilled it out:

Drill the bolt all the way through that is going in the upper hole on the passenger's side of the engine.

In other words, the hole made by the factory in the left oil gallery is not an adequate substitute for the hollow right-hand bolt?

Just want to make sure I'm not opening two holes to do the same thing, thus possibly affecting overall pressure.

-Kurt

 

[RustyRatRod]

Nevermind.

 

[RJK3]

Nevermind.

lol

 

[cudak888]

Does that mean I did it right, or is that sarcasm?

Mind you, I have no problem removing the chain and pinning the tensionier again to put the drilled bolt in, or even knocking out the welch plug and replacing it with a solid cap - provided it's not a duplication of effort for the same result. Either way, I knew I had to drill that hole in the timing chain tensioner - or replace that welch plug.

EDIT: I'm looking at the oiling diagram for the LA. From what I can see, the right oil gallery is pressurized towards the front of the engine, delivering oil to the crank and rod journals, while the left gallery does the same from the front of the engine to the back.

Fair enough - I can see where this welch plug setup would slightly lower pressure on that side, but how does the bolt interact with the right oil gallery? Small passage? Something that wouldn't affect overall pressure as much as the welch plug? Either of the two holes to choose from (welch or bolt) are pretty much lined up directly with the timing chain and cam sprocket, so if oil pressure isn't an issue with a hole this size, it would seem to me as if both methods would get oil where it belongs.

Only benefit of the bolt (at least, from my casual observation at this point) is that it's closer to the timing chain than the welch plug; thus, more likely to oil properly.

-Kurt

 

[toolmanmike]

Here's a pic of what I did. I drilled the plate and drilled a hole in the plug. It aparently works.

 

[Cudafever]

Your find. There's more then one way to skin a cat! The early LA blocks just did it differently.

 

[moper]

The factory had open holes, dripper things, drilled bolts, and all oil blocked off. To be honest they found it doesn't matter - so they deleted the steps taken to deliver more oil there. There's a bunch of oil that gets blown around the crankcase to splash oil the chain. You certainly can augment that with a hole, or bolt with a hole, or leave a bolt ouit, a or dripper thingy, but it doesn't really make a difference.

 

[rumblefish360]

In other words, the hole made by the factory in the left oil gallery is not an adequate substitute for the hollow right-hand bolt?

-Kurt

Kurt, the second you wrote, "In other words" you put words into Rusty's mouth. Then you question him on it. Since you asked the question, what in the world would make you think he would lie to you, talk **** and make stuff up?

Your a real class act aren't ya?

Please, refrain from asking questions and pick up a service manual and figure it out yourself.

(Holy G's, what a piece of work this guys is!!!!!!)

 

[cudak888]

First, thank you to those who replied with helpful advice. I'll reply later when I have a bit more time.

Kurt, the second you wrote, "In other words" you put words into Rusty's mouth. Then you question him on it. Since you asked the question, what in the world would make you think he would lie to you, talk **** and make stuff up?

Your a real class act aren't ya?

Please, refrain from asking questions and pick up a service manual and figure it out yourself.

(Holy G's, what a piece of work this guys is!!!!!!)

On the contrary, I wanted to know the engineering difference between using one hole vs. the other. I would rather be 100% educated on what I'm doing to my engine before leaving anything to chance. Why? I like to know. I like to be able to explain to someone what I did to my engine and why, and share it with others.

I was not questioning his advice; all I wanted to do is learn why one method is superior to another. I'm no engine savant; what I know is based on all self-taught thanks to the brilliance of the learned people on the internet who share their knowledge.

Also, as some of the other posters mentioned, Chrysler modified the oiling on these engines many times over. No service manual covers this modification or the benefits of one method over the other, especially when throwing the tensioner into the mix. I don't see why I should experiment with my engine for the next two years to find out why one oiling method is superior to another when the knowledge exists.

-Kurt

 

[RustyRatRod]

I have not seen the variations moper seems to have. I have torn down I know over a thousand engines over time and to date I have not seen one single one that ever had a hold drilled through the camshaft thrust plate. Not one. That certainly means little as many engines were made. I do agree though that that area probably gets enough oil regardless of what holes are where, or even if no holes are there at all. I always simply drill the upper passenger's side bolt with a through hole, since it goes through to the bottom of the intake valley. I have torn down some known original engines and seen that bolt drilled from the factory. What you have done to yours won't hurt a thing. I simply said "Nevermind" because you asked about something and then pretty much did it yourself.

 

[cudak888]

Here's a pic of what I did. I drilled the plate and drilled a hole in the plug. It aparently works.

I see what you did on the left side - but it looks as if the welch plug behind it is still solid, so I can't quite make out your modification.

Out of curiosity, any photos since installation and use?

Your find. There's more then one way to skin a cat! The early LA blocks just did it differently.

From what I've seen, Chrysler used at least three different combos - plate w/drilled bolt, plate w/o drilled bolt and pinched welch plug, and a plate with no provision for oiling on the Magnums. I'm sure I've missed one variant. Or two. Or three.

The factory had open holes, dripper things, drilled bolts, and all oil blocked off. To be honest they found it doesn't matter - so they deleted the steps taken to deliver more oil there. There's a bunch of oil that gets blown around the crankcase to splash oil the chain. You certainly can augment that with a hole, or bolt with a hole, or leave a bolt ouit, a or dripper thingy, but it doesn't really make a difference.

Makes sense - and with that safeguard in place, I feel a lot more comfortable leaving well enough alone with the way it is now.

I have not seen the variations moper seems to have. I have torn down I know over a thousand engines over time and to date I have not seen one single one that ever had a hold drilled through the camshaft thrust plate. Not one. That certainly means little as many engines were made.

I had a feeling this little hole isn't exactly typical. In all my searches, I found exactly one other plate with that hole on it, and it was a 3.9L thrust plate with the built-in tensioner - so I'm sure someone drilled it.

I do agree though that that area probably gets enough oil regardless of what holes are where, or even if no holes are there at all. I always simply drill the upper passenger's side bolt with a through hole, since it goes through to the bottom of the intake valley. I have torn down some known original engines and seen that bolt drilled from the factory. What you have done to yours won't hurt a thing. I simply said "Nevermind" because you asked about something and then pretty much did it yourself.

I can see now where it might have been taken the wrong way - I decided to drill and install the plate (and take the photo) before I saw your post. I had intended to add a follow-up to my own original post, but yours had come in in the meantime.

I'm sorry if it sounded like I ignored your advice and did whatever the hell I wanted. No hard feelings?

That said, I knew one thing when I drilled the plate for the hole: If I did the wrong thing, I could always replace the welch plug and reverse the modification.

At any rate, even though I'm happy with the setup as it is, you've convinced me to dig up a drilled bolt before I seal up the engine. Going to leave the welch plug hole open too; can't hurt.

-Kurt

 

[Darter6]

Yes, thru the years Ma Mopar did it many ways.all seem to work. This photo is a 68 273 with not a hole anywhere.But it did have a crank oil slinger behind the seal..

 

[RustyRatRod]

I can see now where it might have been taken the wrong way - I decided to drill and install the plate (and take the photo) before I saw your post. I had intended to add a follow-up to my own original post, but yours had come in in the meantime.

I'm sorry if it sounded like I ignored your advice and did whatever the hell I wanted. No hard feelings?

That said, I knew one thing when I drilled the plate for the hole: If I did the wrong thing, I could always replace the welch plug and reverse the modification.

At any rate, even though I'm happy with the setup as it is, you've convinced me to dig up a drilled bolt before I seal up the engine. Going to leave the welch plug hole open too; can't hurt.

-Kurt

Naw I didn't take it that way at all. I just meant you pretty much solved it yourself. It's all good.