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Mack 2v can it be changed to 4v?


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Long time lurker and reader. I recently started blowing compression in to the radiator on my 81 dump.  Planning on doing an inframe but seems as tho 2v heads are obsolete....based on several calls...Called bruckners and watts....plus some others. I have noticed 4v heads are still avaliable and use the same head gasket. Beyond that I know nothing....

So has anyone one done it? I don't really have the time for the truck to be down for ever...I am looking for a good engine either e6 4v or e7 mech around me as well.

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From what I have heard there is a laundry list things that are different between the two motors. It probably would be easier to find and swap in a 4 valve E6 than to try and convert a 2 valve. Do you know for certain the heads are junk? Lots of things to troubleshoot before condemning the heads! 

Also Welcome to the forum! 

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41 minutes ago, BOBWhite said:

From what I have heard there is a laundry list things that are different between the two motors. It probably would be easier to find and swap in a 4 valve E6 than to try and convert a 2 valve. Do you know for certain the heads are junk? Lots of things to troubleshoot before condemning the heads! 

Also Welcome to the forum! 

No not sure they are bad but have never seen a set that wasn't cracked.  I was wanting to get it back together in less than a week...as I have alot of work for it in places my other trucks can't get to. I will know soon enough I type this as I set on the steer tire...should have the heads off in a few more hrs.

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There will be plenty of cracks in the heads, they will be all over the place 

Especially around the injectors

Most times this isn't a issue at all, have them checked to see if they are leaking thru the cracks 

If all is okay then just have them done up

Paul

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So far they look alright. #2 was getting water in it and communicated with 3 looks like. Thanks for the responses....now to find a machine shop that can get it done in a reasonable amount of time and get my rebuild kit ordered.

20240729_191555.jpg

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16 minutes ago, fjh said:

Just wanted to mention that a member just did a head gasket re/re a month back here! My self I would just clean er up and take a chance! It’s old! The fire ring groves can be an issue if the shop ain’t set up for it! As mentioned!

just sayin 

 

Hey ; what's this "it's old take a chance" ;; now i feel offended. LOL . it's NOT old ; it's mature .  I'm a two valve ; new valves in "15 still tickin. LOL

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Posted (edited)

I didn't even notice the fire ring grooves if there was any.... but I have been around that on high boosted pickups and trucks. But nothing stuck out on the heads I will have to look at that.

I haven't got the injectors out yet....was going to fight that battle in the am. The rockers looked good but had a bad push rod...the bottom ball fell out. I fished it out tho. I plan on pulling the injection pump as I had some leaks and send it and injectors out. It also needs a compressor as it slobbers alot of oil.

I did find a good set of used heads if I need them tho. I was going to call about a inframe kit in the am as it could use it.

Thanks for all the help and advice

Edited by Dieselsmoke138
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PAI should have what you need as far as gasket kits. Check out thier inventory.  You may only be able to buy parts through a vendor, and not directly from PAI..

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Some thoughts 

As Geoff Weeks would say, fix any air leaks first

But if it doesn't leak air, change the compressor, rebuild kits are available for most compressors

I personally dont stuff about rebuilding them and just put a tested reco compressor on

As Joey said PAI  have just about everything you will need

Mack, in Australia at least has all or any rocker gear you will need

If possible, I would have the heads rebuilt rather than put a a used set on 

A used set is a unknown, a rebuilt set should be as good as new 

I personally fix everything that is possibly wrong when I have it in bits,  it's off the road sdo fix everything 

 

Paul

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13 hours ago, mechohaulic said:

Hey ; what's this "it's old take a chance" ;; now i feel offended. LOL . it's NOT old ; it's mature .  I'm a two valve ; new valves in "15 still tickin. LOL

politically correct term ( elderly  ) My wokeness  escaped me when I posted  bro sorry! It was early I wasn't awake! 😁  for give me  I'm usually more polite !

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Blow-by in the engine can effect the compressor, so I wouldn't condemn it until the engine is fixed and the air leaks are gone.

 Compressors are made for "duty cycles" meaning that much (way more than 1/2) of time they are (or should be) running "unloaded".  If they are compressing most of the time, they will slobber.

 Every time I see a two valve Mack head, I think of how similar they look to a Leyland 680 head! I swear, somebody copied somebody else.

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Posted (edited)
5 hours ago, mrsmackpaul said:

Some thoughts 

As Geoff Weeks would say, fix any air leaks first

But if it doesn't leak air, change the compressor, rebuild kits are available for most compressors

I personally dont stuff about rebuilding them and just put a tested reco compressor on

As Joey said PAI  have just about everything you will need

Mack, in Australia at least has all or any rocker gear you will need

If possible, I would have the heads rebuilt rather than put a a used set on 

A used set is a unknown, a rebuilt set should be as good as new 

I personally fix everything that is possibly wrong when I have it in bits,  it's off the road sdo fix everything 

 

Paul

I doesn't leak much air will hold 30-60 lbs over night but it pukes alot of oil.

I plan on going thru everything while I have it down. Just got injectors pulled out of the head...will prob have the heads cleaned up and new seals. I found a shop that can cut the rings if needed but are a month out. A week just to clean them up but I figure will take close tp that for everything else.  Plan on pulling the pump and having it gone thru....

Debating doing lower end as had some blow by drips....but haven't decided.

 

Joey I may hit you up for a pair. I had to add it to this post as I have reached my max post for the day apparently...lol

Edited by Dieselsmoke138
to add since no more post for the day
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It is not what it will hold overnight, it is how often it "blows off" going down the road that matters. I've seen leaks on the "wet" side, while the primary and secondary air tanks and components will hold overnight.  Air line from compressor to the drier (if used) check valve in drier, air line to the wet tank, air line from the wet tank to other tanks, air line to air gov from wet tank, wet tank itself. air gov. All of those can leak and cause the compressor to keep cycling while the two main tanks hold just fine.

I had one guy idling next to me in the truckstop, air system popping off every 15 sec, I told him he had problems, he said "I didn't know what I was talking about, his air system was the best in any truck he'd ever seen, stays rock solid on 120 PSI"! 

 Best test I know, is run down the interstate at highway speed, when you don't have to touch the brakes for a while and time how long between when the compressor "blows off",  Min acceptable to me is 10 min, 15 to 30 your just doing ok. 45 min and you have one tight air system.

 If you can pass that test, then you can condemn the compressor if it is still slobbering and the engine blow by is in check. 

Edited by Geoff Weeks
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