Mechanics

HEAD GASKET CHANGE HELP

2000 Dodge Dakota

Engine Mechanical problem
2000 Dodge Dakota 6 cyl Two Wheel Drive Automatic

Well, been working on this v6 2000 3.9 l Dakota that my brother said overheated and started blowing white smoke. I have the heads off and wanted to make some comments and get some advice:

1: This is the first time I have worked on a dodge. I thought the distributor would need to come out in order to take the intake off. I took off the mounting clamp for the distributor. I made a mark with a sharpie on the " plate" that is on top of the distributor base below the rotor. I made the mark in the direction the rotor was pointing. (The best I could, it was hard to see back there.) I actually never took the distributor out. When putting this back together, can I just aline the rotor with this mark. If it is off a 1/4 inch will it matter or do I need to do something different?

2: I took all head bolts out and pushrods and punched holes in two shoeboxes to store them to keep them in order. How do I tell if the head bolts need replaced? Also, the push rods had a clack coating on them. DO they need to be cleaned? Also, an old manual to another car said to put grease on the top of the pushrod the area the rocker arm contacts. Is this good advice or will it block oil flow?

3. The back piston where I had high compression and was blowing coolant out the spark plug hole was about two inches from the top. I felt around and used a mirror and did not see anything wrong. Should I turn the engine over so I can inspect the rest of the bore? Will this disturb timing?

4: On this same piston there are two areas where a small " glob" of metal apparently attached to the piston. In this same cylinder during disassembly, the spark plug gap arm was missing. They are about the size of a baby asprin. I could not pry them loose with my finger. Should I try a razor blade? Is this really bad?

5: I am not sure if I am looking for is right but the head gasket looked alright to me. There were no " blown out" areas where gasket material was missing between cylinders or anything. Does this mean it might not be the head gasket?

6: Lastly, I am going to have a shop mill and crack check the heads. If they hot tank them, will this mess up the valve seals? Should I have them replaced? This engine has about 151,000 and ran ok when disassembled other than the overhweatign and smoke assumed from a leaking head gasket and anti freeze in the intake. I may drive this truck if it runs or sell it, not sure.

7: Oh, one last thing, some " leaf" material fell into the engine when I took the intake off. I vacuumed it as much as I could but did not get it perfect. Will this be a problem?

As always I appreciate your help!
Avatar
Stryped
April 13, 2009.




Thank you for providing some good details. You're going to be pleasantly surprised because working on most Chrysler products is WAY easier than on any comparable GM product.

You shouldn't have to remove the distributor. The rotor can't be off only 1/4" because there aren't that many teeth on the gear. Also, if it's built like they did years ago, the shaft has a screwdriver blade on the end, not a gear like GMs and Fords. That means the shaft will only go in two ways and the rotor will not turn as the distributor is dropped down.

You did right to keep the pushrods in order. Any moving parts should be kept with their mating parts. They are not hollow like GM pushrods so no cleaning is required. You will see a bump in the head castings where oil comes up through a feed passage from two cam bearings, one on each side. The passage can be seen next to the threaded rocker arm shaft bolt hole. The hollow shaft gets pressurized oil from that passage, and the oil is forced out through the holes in the bottom of the shaft onto the rocker arms. GMs just spray oil through a hole in the end of the rocker arm and hope that some lands on the rocker arm pivot. A little engine oil on the contact points between the pushrods and rocker arms is sufficient; engine assembly lube is better, but nothing will happen if you put them together dry. The oil will be up there within a few seconds after starting. Don't use any kind of wheel bearing or suspension parts grease inside the engine. It will melt into the oil ok, but then it will collect and solidify in the oil filter, plugging the filter. There's a bypass valve if that happens but then unfiltered oil gets to the bearings. Engine assembly lube melts into the warm oil and stays in suspension until it is drained. For the little work you're doing, I wouldn't even waste any money on a tube of assembly lube. Just dunk the pushrods in some clean oil.

The timing will not be disturbed if you don't pull the distributor out. You can turn the engine by hand to inspect the bore, but a cracked cylinder head is a lot more likely. Coolant coming out of the spark plug hole is a good observation that a lot of people miss. A cracked head would explain why the gasket looked ok.

You definitely want to get that blob of metal off the piston, otherwise it will dislodge, and could score the cylinder wall or jamb a valve open when it tries to escape. Bring that piston up as high as possible, then lightly tap sideways on the blob with a hammer and small chisel. If the spark plug electrode melted off, that will be steel. It may have melted into the aluminum piston, but it won't stick real well. Scrape or carefully grind off and high spots or ridges left in the piston top to prevent hot spots that can cause preignition / knocking. Line the cylinder with rags before grinding to catch any particles. Also wipe or suck out as much coolant from the cylinders as possible to prevent it from running past the piston rings into the oil. Antifreeze dissolves the soft metal engine bearings. It's a real good idea too to change the oil after the engine is warmed up.

Ask the guys at the machine shop about valve seals and head bolts. I'd go for new seals based on mileage and because you're half way there already. These rarely cause a problem, but why risk it? Head bolts are most often replaced won engines with aluminum heads. Proper clamping forces can't be measured with a torque wrench because the aluminum will just crush. Instead, some applications, GM in particular, have you torque the bolts to a low value, say 30 foot / pounds, then turn the bolts a specified number of degrees. You need a " torque angle gauge" for that, and the values are pretty critical. A lot of Chryslers just say a low specified torque, then a quarter turn. They aren't as picky. The head bolts that must be replaced are those that stretch when they are tightened. They can only do that once. I don't think you need to replace your head bolts but the machine shop guys will know for sure.

After you vacuum out any crap that fell into the engine, cover it with rags to keep it clean. Anything that fell down into the oil pan will be collected by the screen in the pickup assembly. If it makes it through that screen, as long as it's not metal, will get stuck in the oil filter.

Caradiodoc
Apr 15, 2009.


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