Roy's Garage: '90 2.4-4G64 5-spd D-50

[royster]

BradMPH has provided a great information resource for valve guide seals HERE.

Oil consumption is discussed HERE.

And thillskier testifies HERE about oil consumption/smoking eliminated by replacing valve guide seals.

As so many of our problems seem to be from engines smoking heavily...many of them are up to a pack-and-a-half a day ...it has been my observation that 85% of the problems can be traced to worn valve guide seals. That is definitely the case with my 2.4.

I also discovered two valve guides have slipped out of place, and in the worst location: #4 and 3 exhaust, which are at the back of the engine in the area oil gathers most when the engine is shut off. These guides slipping down caused the valve seals to dislodge and become useless. The symptom was extreme engine smoking at cold start-up. Once the engine was warmed, the smoking was minimal: an occassional cigar at worst.

If your truck is smoking, and a nicotine patch isn't working, look into replacing the valve guide seals before you panic about an expensive rebuild. They CAN be replaced while the head is still on the engine, though caution must be taken to assure valves don't slip into the cylinder when the keepers and springs are removed. The Chilton manual suggests setting the cylinder you're working on to be set at just-before TDC, the spark plug removed, and the cylinder stuffed with nylon rope. Once rope is stuffed as much as you can, turn the engine gently to TDC. The rope will support the valve while you replace the guides. After each cylder is serviced, back the engine to just-before TDC and remove the rope. (See the book or ask here if this suggestion isn't clear).

[royster]

I await the arrival of a new oil pump, will post about the experience next week.

[royster]

I await the arrival of a new oil pump, will post about the experience next week.

RockAuto just e-mailed a shipping notice. Not much I can do in this single-digit weather: I'm stuck in two rooms of the house: the kitchen or my studio. But I brought the valve cover over to the house with some aluminum polish and fine steel wool, to make good use of down-time.

Shortly after i got my D-50, I began to notice a gas leak, which was obviously at the tank. During the week I had the truck up on jacks in my garage, I dropped the tank, thinking it was a simple rubber connection gone bad. It turned out to be the metal tubing coming from the fuel pump: it has corroded through, just enough to start leaking.
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I ended up breaking the tubing worse while trying to repair it. I had 1/4" stubs to try and attach fuel line to. Using the concrete caulking I talked about earlier, I literally caulked new rubber fuel line onto the stubs, carefully hose-clamped them on, surrounded that with more caulk, and let the repair sit for at least 48 hours. I then made a "shell" over the repair area with Bondo, about 1" thick, to keep it from ever moving.

The repair was a success, though I need to get a higher rated pressure fuel line in.
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The cats helped me ready the garage for the truck repairs. I had the Sable in there for a week, replacing sensors and other engine fussing. When it came time to back it out of the garage, Castor steered, while his sister stood on the gas pedal.

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For those who know: yes, that's a Big Book on the Sable's rear deck.

Don't know if I shared this, yet, or not: They LOVE to drive...
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all three of the cats will go into the creek to hunt...
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and they are very adept at working on cars...
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[royster]

CYLINDER HEAD / VALVE GUIDE UPDATE

The machine shop just called me, the machinist, himself...Mark. He has been working on Mitsubishi engines for many years...how lucky can I be?

The EXHAUST valve guide pushing down, and disengaging the valve seal, was common to these (and other Mitsubishi) engines. The reason is simple: iron and aluminum...particularly the exhaust valve, where temperature causing expansion/contraction is more dramatic. He told me he bought a tool several years ago that scored a groove in the valve guide which allowed him to put a snap ring on top to keep it in place. He went on to say that Chrsyler eventually put snap rings on the valve guides at the factory to solve this problem, making his tool sort of obsolete. He said a mechanic's life is like that: things come and go in waves.

He proposed to push the existing valve guides back into place, and use his special tool to put snap rings on the guides. He said he hasn't used that tool in five years.

As I once had an '88 Dodge Caravan, I know about the smoking-at-idle, and knew enough to suspect valve guides. But in this past month, I've learned volumes about how the guides and seals actually work.

So it was all good news: no cracked head -HEY! CRACKED HEAD, not CRACK-HEAD! - and hopefully the head returns tomorrow...in time for the better weather and remaining parts to be delivered.

[royster]

When the time comes for a head rebuild, I'd be prone to cut grooves in the valve guides before replacing the assembly. Mark, the machinist, said that the snap rings were hard to come by, any more. Like so many things on these trucks, we have to resort to what's available.

I drew a picture to show how the valve guides fit, and where a groove-and-snap-ring would do the most good. Mark says that without the snap rings, the repair lasts only one year: the problem returns.

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More than being worried about The Beave, I'm suspicious of that Eddie Haskell. I've heard rumors about him.

[royster]

The Fed-Ex guy just left after dropping off my oil pump and other goodies.

I got the cylinder head back this morning and I have everything I need to get back to work on the Tin Can, including 50 degree weather for a few days, above-freezing at night.

In theory, when this engine is put back together, it will be better than ever...or at least, any smoking will be absolutely minimal: there's no question I've addressed the core problem of the oil burning.

Will be taking pics to post.

Time to fire up the kerosene heater!

[royster]

I started trying to install the valve guide seals, but was a bit stumped by the "o" rings that came with the package.

The book, again, says NOTHING about installing valve guide seals except "install them". Well, wonderful, but there's nothing to go by, except to look at the part, and the part it fits on. It should go this way or that, but no definitive instructions anywhere. I assume the plastic is all that goes in place (without the "o" rings) and that's enough to keep oil out. Guaging by the distance from the top of the guide to the groove the seal is supposed to fit on, it doesn't seem to match up. How far down do you go? Does that beveled groove self-tap the seal? I'd hate to go through all this trouble and have it fail...simply because I can't find a simple answer to a simple question.

This is one situation I DON'T want to learn from failure: these seals not working right means tearing this thing down again. I was unable to locate any threads here regarding the actual process of installing valve guide seals.

Help



And for all my careful bagging of each individual valve assembly, I somehow lost two or three spring bases. WTF? That's when I knew it was time to walk away for the night before I started

Tomorrow I will start by doing a good clean up and organizing everything: stuff's getting scattered and misplaced. I must say, in good faith, that I'm glad to be back out there after the freezing weather. And getting frustrated is no way to enjoy the project, OR do good work.

EDIT: This was of some assistance: thanks Brad MPH~
http://www.mightyram50.net/vbulletin...uide-Seals-101