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

[royster]

Analysis From Evidence

I had suspected that ADDING TOO THICK OF AN OIL caused undue resistance on the camshaft during very cold temperatures, stressing the timing belt and causing it to strip out. Evidence shows this to be only part of the answer.

The center cam shaft bearing area has a "glob" of aluminum fused into grooves worn from any number of reasons, but suffice it to say that the oil passages in the cam shaft are very small, and thick oil (in cold weather) did not allow proper lubrication. Likely a dry spot on the bearing broke off (metal shavings in the drained oil) and fused itself into the bearing. This caused high and low points on that bearing area. (I say "area" because there are no replaceable bearings, this is the aluminum head and two-bolt hold-down machined to hold the cam shaft in place. RockAuto.com offers a bearing sleeve to repair just such damages, but that's another chapter).

This high point in the middle of the cam shaft caused even more resistance as the engine turned, making a "teeter~totter" affect. When the cam shaft is laid in the cylinder head craddle, I can move either end up and down due to the "bump" fused into the bearing area.

Very carefully scrutinizing the 2.0 cam shaft bearing holders, I can swap them to minimise the damage (and avoid ordering expensive parts) leaving me with only one damaged surface on the cylinder head, itself. I intend to use a Dremmel tool to carefully grind down the high point, then polish the surface. The cam shaft isn't damaged excessively.

This motor has 217,000 miles on it, and although these motors are pretty darned hearty, I only want to buy myself some time so I can locate a rebuildable 2.4 while this one still gives service. It is for this reason I decided not to go to the trouble and expense of replacing the water pump or oil pump: both seem to be in good service. However, I am taking the time to assure oil passages are cleaned, intake manifold and sytems are cleaned, and replacing sensors that affect the cold idle and choke: they hadn't been working since I bought the truck.

I wish I could take the time to do some gratuitous paint detail, but the days here are 40 degrees at best, 25 at night, and painting in an enclosed garage with a kerosene heater burning is about as smart as electing Sarah Palin for President. It can be done, but the results might not be satisfying.

[royster]

I'm thinking it might be because of the oil pump sprocket.. am I correct in thinking that there's a balance shaft behind it too? I was pretty sure there was 2, but not sure. I spent alot of time on the other side that has the balance shaft belt. I aligned the oil pump sprocket with its timing mark.. But that was it. Didn't think I really needed to do the next step.
http://www.mightyram50.net/vbulletin...ull=1#post3764

can anyone tell me where exactly this bolt is? I looked on the drivers side of the engine and saw what I thought to be it back towards the starter. . . .Alright, well to answer my own question.. yes, there is a bolt back by the starter on the block. That is the access hole to the determine if the balance shaft is aligned properly. Skipping this step will only cause you headaches.

Thanks to blindeyed's posts, I was made aware of the other silent shaft access. I located the bolt and assured that's what it was. (The Chilton book mentions very little about the balance shafts, not sure how the Hayne's book measures up, but I find the book lacks in some simple areas like this. If we know, we can DO. If the feature is just shrugged off or casually mentioned, it doesn't help the beginner much).

On the passenger side of the engine it appears (gulp) the access is through a phillips screw, that I'm hoping to Gawd will come out without stripping. However it comes out, I'm going to replace it with a bolt of the same size.
[EDIT: these screws only access the bearings for the silent shaft]

I'm still working on the bench, so the block-in-truck work really hasn't started, yet. I got the 'bearing' ground down and polished pretty nicely, and successfully exchanged the 2-bolt hold down for that bearing area. I'm making sure absolutely ALL oil passages are clean.

I cleaned up the head about as good as it's going to get, and will start replacing valve seals tomorrow...good use of time while waiting for the replacement valves to arrive. I'll also order new hydrolic lifters from NAPA locally.

In the manifold and plenum, the EGR passages were really blocked, so I've taken great care to clean the passages out really good. Anal-retentive clean is what I'm aiming for in all aspects of the repair.

Before the head goes on, I'll drain the cleaning oil I had put through the motor. Once everything is assembled, I'll pour some more clean oil (10-30) around the whole assembly and crank the motor to push good oil through the passages, then drain that before the initial start up test. I think I'll be alright using straight 30 weight, unless one of you experts tell me not to.

And as was advised, I'll keep an eye on the mileage and re-torque the head at 500 miles. So all the wiring and such isn't going to get tucked neatly away, just yet.

I'm very thankful for all the information on this forum, and know how hard-earned much of it was...like blindeyed's experiences. It is my hope to present my own experiences (and that which I learned to avoid) for those coming down the road in their recently-acquired Mitsubishi trucks. I've taken pictures of many things during this process and when they're developed will post them.

[royster]

The engine compartment, note cylinder #3
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I HAVE to do a good job: I'm constantly being watched.
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Securing bolts in the order they go.
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An overhead view of the work bench. Note the small flashlight on the cylinder head: with the overhead lights off, this light reveals the high and low points by casting a shadow. Auto body work is done the same way, as is good drywall mud-work.
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Lots of cleaning to do...and lots of cleaning up getting done.
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[royster]

I was in Woodstock (Virginia) ordering hydrolic lifters from my NAPA friend. I told him that NOW I knew what he meant by those "jet ports", having just torn down a 2.0. He said what he used to do with the jet ports was to weld them shut. On the '90 with fuel injection, I don't have to worry about that.

As he has been a parts man and racing mechanic for over 30 years, I value his expertise. I asked his suggestion about preparing the hydrolic lifters for installation. He said a 50-50 mix of "Mystery Oil" or STP and transmission fluid. If possible, soak them overnight with the holes up. They will not need adjusting. It's cool to note on the 2.4 4G64 the lifters have rollers on them: there''s virtually no friction on the cam contact.

I am about done with Advanced Auto parts. And UPS: I have had orders left out on my driveway, and today the driver was in my neighbor's driveway, trying to figure out how to get off the hill in this snow, seriously pondering the most dangerous place to turn around. I asked if he had my part...(Advanced found it appropriate to send a thermostat gasket from a large order, by itself, in a ridiculously large container)...which he did. I then gave him back-woods advice as to how to get off the hill safely: there was no way he was going back the way he came. There's a road out if you continue down the hill, past my driveway. I hope he made it out okay.

RockAuto.com uses a variety of delivery services, and the valves I ordered are coming FedEx. NAPA has a warehouse not from from here, in Winchester. I'm essentially dealing directly with them, often getting next-day delivery at the store.

There are some parts you simply can't get from a supplier, any more, and you'll have to resort to making them yourself, or getting them from a junkyard. Timing belt cover seals aren't to be found. My NAPA friend said to bring the old seal/gasket in, and we can determine which material to make a new one from. This seal is important as it keeps dirt and oil off your timing belt.

[royster]

BIG Discovery

While examining the valve assembly still on the head, I found that the #4 exhaust valve seal was mid-way UP the valve stem. I had wondered WHY so much oil was at the rear of the engine, and now I have a good answer. The seal had worked its way up...faulty installation or whatever...and was letting oil go everywhere, particularly into the exhaust manifold. Therefore, every cold start included the serious smoking I had been worried about in the first place. [Thinking it was rings, I used thick oil to curtail the smoking. This caused the timing belt to strip because the camshaft couldn't move freely.] It seems lessons are learned every day, if you're really paying attention.

How else but by chaos would I have learned (and discovered) all of this?

The WAS no other way. Experience is often prompted by necessity, and necessity often comes from our mis-conceived ideas. We make mistakes in order to learn.
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The valve seals sent in this kit include 4 exhaust seals, and 4 intake "positive" seals. Both are going to take some reading up on before I am confident to make the repair.

Speak up, you experts, please: I could use some advice on installing two different types of valve seals. The "positive intake" seals have two aluminum rings around them. The exhaust seals are identical replacements. At present, I only have #1 intake valve out of the head, and its seal looks like the other 7.
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Don't know if the scan will show it, but the photograph does: #1 intake valve is out (for your orientation). The #4 exhaust valve seal can be seen higher than the others (if the scan picked it up). [edit: it did.]
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IN OTHER NEWS...
Once the parts truck was removed from the garage, I took the time to clean up real good, and also install these bargain cabinets I got for $40 from Lowe's discount aisle. Drawers and cabinet space in a garage are a real treasure.

I also laid down 2 pieces of new Luann plywood for the next project (the one underway right now).
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View of my sitting area where I read the manual and have coffee. The steps to the right lead to a small storage room behind the garage.

Note the air filter in the canister: this is a ShopVac filter from Lowe's. It takes only placing a notch in the filter bottom rubber for it to be a perfect fit in the 2.4 4G64 air filter canister.
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[royster]

IF IT DOESN'T FEEL RIGHT, IT PROBABLY ISN'T
No "first-wife" joke here: it's too obvious.

The valve stem seals that came with my head gasket set didn't seem right...because they aren't. Having removed the exhaust valve I posted about, I compared the replacement seal with the worn one. I even set it place, expecting to hear a "click" as it snapped over the groove designed to hold it in place. The new seal doesn't have the ring that snaps into that groove. Several "first-wife" jokes could be used here. Like, "If I used these seals, they'd just be flopping around in there, doing no good."

One problem with locating replacement seals is the illustrations that most websites offer: they do not show a cut-away view.

So tomorrow, when I go to pick up my lifters, I'll ask my NAPA guy if he has these in stock, and if not, to help me locate the right part. I'll take the two used seals with me to be sure (one intake, one exhaust).

This frikken' 'journey' is frought with all KINDS of traps and pit-falls! It makes me even more appreciative of this automotive community.

The Chilton book mentions very little about the balance shafts, not sure how the Hayne's book measures up, but I find the book lacks in some simple areas like this. If we know, we can DO. If the feature is just shrugged off or casually mentioned, it doesn't help the beginner much)

This applies to the seals, too: the book simply says to put them on. No cautions, no what-to-look-for's, no first wife jokes. "Common sense" picks up where book-smarts leave off, and so the name of this post is "If it doesn't feel right, it probably isn't." So stop and take the time to figure out how to make/do it right. Force doesn't always make something work. And just "hoping it works" is a fatal flaw. [First wife joke #197]
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The book tells you that if the valve doesn't spin freely on its seat, it's probably bent or warped. In most cases, this would be true. However, the exhaust valve I removed had become stuck in position due to long-term build up of carbon from leaking oil. The wire wheel on my Dremel tool cleaned that area to the point that the vlave once again fit happily, and rotates as it should.

I am reminded the book is ONLY a guide-line: it's up to us to THINK, and to proceed with focused attention.

And it's up to us to share these insights, or the experience is no good for anyone. [First wife joke #583]