My 5.9 Magnum Build - Junk Yard Mule

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Haney

www.carsonandironmt.com
Joined
Jan 14, 2005
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Location
Piney Flats, Tennessee
I have had a 5.9 Magnum out of a 98 Ram that I traded a set of wheels and tires for over 8 years ago. It has sat in my garage ever since just waiting for an opportunity to live again. It is supposed to have come from a running truck with 80K miles. Fast forward, I have acquired an 84 Ram W-150 that needs a new motor. My plan was to tear down, use the long block, 1984 timing cover and accessories, an intake and a carb. I plan to use the existing truck manifolds, ignition and fuel pump. I did order a new cam, a Hughes Long Snout 208/214 @ .050 0.532/0.533 lift and their springs and retainers. I also got a new timing chain and oil pump.

I tore down the motor last night and it was not as clean as I had hoped. Some things that concern me.

· How much carbon was on the pistons, could not have been running very well.

· Lifters on #8 and exhaust on #7 would not come out still working on them. Motor turned over good so they are not stuck in the lift range.

· #4 cam bearing is pretty bad

· Timing chain worn pretty good

· 7 of the 8 plugs looked old but the plug on #8 looked really bad. Lots of detonation? What would cause this?

Attached are some pictures. Do you guys see anything that concerns you?

The cylinder walls still look great (still see cross hatching and not ridge). I plan to check the main and rod bearings. If they look good, I plan to change the cam bearings then put it together and run it. Is this a good decision? Based on what you see, is there anything else I should do/check? This will just be a driver and not a Mopar Muscle Truck (MMT). Lol.


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well, I'll start with #8 plug. Typical for them to loose the plenum gasket underneath the intake. Oil enters cylinder, and usually number 8 is the first to receive it.
 
well, I'll start with #8 plug. Typical for them to loose the plenum gasket underneath the intake. Oil enters cylinder, and usually number 8 is the first to receive it.
I totally forgot about the plenum gasket deal. I will check under that intake. Even though I am using a dual plane Mopar Carp intake on my build, I would like to know what caused the things I am seeing.
 
Looks pretty much like any 5.9 ive ever torn down. Clean everything up, and put it all back together. +1 on plenum gasket failure. While you have your heads apart to put the new springs in i would suggest a valve job, at the very least lap them in, doesnt look like they were leaking between the seats so you should be good to go. I would bet the lower end bearings are fine, however a new set is like ~60 bucks, just good insurance. i also like to use the mr. gasket 1121g head gaskets for a little bump in compression. Should be a stout little truck motor when youre done.
 
Looks pretty much like any 5.9 ive ever torn down. Clean everything up, and put it all back together. +1 on plenum gasket failure. While you have your heads apart to put the new springs in i would suggest a valve job, at the very least lap them in, doesnt look like they were leaking between the seats so you should be good to go. I would bet the lower end bearings are fine, however a new set is like ~60 bucks, just good insurance. i also like to use the mr. gasket 1121g head gaskets for a little bump in compression. Should be a stout little truck motor when youre done.

Thanks for the reply. Yeah, I am trying not to let this thing snowball on me. I was not to worried about the heads, but you make a good point. I was planning on running the 1008 Fel-pros at 0.039 compressed. There are some negative posts about the Mr. Gs. You ever had any trouble with them?
 
Thanks for the reply. Yeah, I am trying not to let this thing snowball on me. I was not to worried about the heads, but you make a good point. I was planning on running the 1008 Fel-pros at 0.039 compressed. There are some negative posts about the Mr. Gs. You ever had any trouble with them?

I've had them on 4 separate motors thus far. 0 issues. And these are head and deck surfaces that were cleaned with a palm sander and 180 grit. Copper spray and done. Some were factory bolts some were arp head bolts.
 
I've had them on 4 separate motors thus far. 0 issues. And these are head and deck surfaces that were cleaned with a palm sander and 180 grit. Copper spray and done. Some were factory bolts some were arp head bolts.
With the added lift of the cam, do you think I would have any issues using the much thinner gaskets?
 
I've got one running 218/224 .528/.536 w/ stock valves and the 1121g. Another running 242/248 .580/.580 with 2.02/1.6 valves, and a previous setup was 242/248 .550/.550 on stock valves. It's always a good idea to check yourself upon assembly but I haven't had any clearance issues yet with any of my combos.
 
That chalky black appearance on the internal surfaces of the block is usually an indicator of poor maintenance, particularly lack of oil changes. I believe the oil gets really acidic and loosens the bond between the bearing material and the steel backing. The cam bearing in your picture is not worn, it is flaking away. If it was mine, I would replace all of bearings, including rods and mains, and carefully inspect the crankshaft bearing surfaces.
Next, you will want to check all the pistons to see if the oil drain holes inside the ring lands are blocked with carbon. This is common on Magnums with lack of maintenance, and maybe a leaking plenum gasket contributes as well.
It will still be a good core to build even if re-using the old pistons.
 
Be sure to check the upper rod shells in particular. They take the hit with the typical detonation from the plenum gasket failure.
 
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