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D25 Engine Rebuild thread


bamfordsgarage

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Yes and no. A healthy engine should not have any pressure inside the crankcase. The bottom of the tube is cut at about a 45 degree angle. When the vehicle is in forward motion this angle cut creates an eddy current or a slight reduction in atmospheric pressure so it actually pulls the fumes from the crankcase when the vehicle is in motion.
The balogna cut at the bottom of the tube, creates and area of low pressure at the bottom of the tube as the airflow from vehicle speed moves around it. This low pressure rather than pressure build up in the crank case is what draws out the vapor. See Bernoulli's principle.

As such the pipe should be vertical so as to expose the greatest area of the cut portion to the air stream.

I stand corrected and have learned why there is a 45 degree angle on the bottom of the tube. Thanks guys.

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Progress today in the house and the garage... our Christmas tree and the D25 engine are now both on proper stands.

My bellhousing was constrained by the alignment dowel pins and some time wasted trying to persuade it to clear the flywheel. A quick search on the forum over lunch revealed that the pins could be tapped out of the block into the bell housing to provide clearance. Less than a minute later the pins were out of the way and the bellhousing off the engine.

Many years ago I thought I lost a fuel pump pivot pin into the sump, but there was no sign of it today — only the pump return spring. Either my memory is faulty (most likely) or it disappeared elasewhere, perhaps jammed up somewhere in the block I haven't yet looked.

I was relieved to see the #2 cylinder wall had not suffered any scoring from the last 3,000 or so miles of driving with a broken top ring. There was some carbon buildup at that point, but no damage. All the cylinder walls look good other than a modest ridge at the top of every one.

There was no obvious indication of why compression was so low in #6.

I've only looked at the #1 rod bearing but was not happy to see significant scoring of both the cap and crank to one side of the centreline.

More photos and comments to follow shortly.

Photos: Fuel pump spring has toured North America down in the oil pan; #2 Cylinder looks real good despite broken ring; #5 and #6 cylinders and valves, no indication of burning; disturbing #1 rod bearing,

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I pulled the rear three Welch plugs — thanks, Don, for the removal tip. The ones behind the cam and immediately above were reasonably clear, but the one to the left was chock full of gunk. I reckon the car will run much cooler once the water jacket is properly cleaned out.

A mystery part showed up in the water jacket when I turned the block upside down — some kind of broken fastener with a notch in the head (photo below). Any suggestions what this might be?

The pressure plate is slightly scored, the flywheel is dead smooth and the clutch disc still had a reasonable amount of lining. Nonetheless, I will replace/reline the disc on general principles. Don, are those blotches you can see on the flywheel and pressure plate the hard spots you mentioned yesterday? And if so, might one want to touch up the surfaces on the grinder or just leave them as is?

This throwout bearing is past due for replacement. Note the hole at the edge — about 15K miles ago in California the throwout bearing started to squeal every morning and from time to time during the day. We didn't have a replacement and were really unmotivated to do that job on the road. So we stopped in at a friend's place in Tulare, CA and used his hoist to get the car up in the air and the dust cover off the clutch. Using a long drill bit we drilled that hole in the throwout bearing housing and squirted it full of grease. The noise stopped and didn't come back until just a few month ago, and even then just occasionally. We carried a replacement bearing with us on our big trip last year, just in case, but never had to install it. Now, obviously, is the time.

Photos: Rear of block, water jacket opened up; Mystery part found in water jacket; Flywheel and disc; Pressure plate and disc; Throwout bearing with lube hole.

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Cool trick with the throwout. the flywheel should be surfaced by your machine shop, they will make sure it is flat and true, and will have a surface that the new friction disc will like. Are you planning on replacing the pressure plate? If not your shop should be able to deal with that also.

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Not sure how it would get in the motor but it really looks like a flywheel bolt compare to one you have.

My 218 has to be bored 0.30 crank was great but the timing chain was close to jumping .

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A mystery part showed up in the water jacket when I turned the block upside down — some kind of broken fastener with a notch in the head (photo below). Any suggestions what this might be?

[/i]

Looks to me like a damaged flywheel bolt. Ah, the mystery!:P

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If there is a big problem with my crank, I may go with the bigger 265 engine internals also generously offered to me by PatS. We’ll have to see.

Chris, I have 251 internals not 265...the original stuff from my 49 Chrysler. The pistons and rings are NORS from 1958. New in the original wrappers.

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Using a razor blade to indicate the size of the mystery piece didn't work well — although it is shaped like a flywheel bolt, the size is much smaller. See photo below for comparison and sizes. Finding this gizmo in the water jacket is a real puzzler to me. It was near the front of the engine... maybe shrapnel from a self-destructing water pump many years ago?

Thanks Pat, I'll be in touch soon.

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Edited by bamfordsgarage
Note to Pat
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As has been mentioned flywheel grinding is a machine shop function not a hand grinder function. Should come back with nice swirl marks as pictured.

Also you can send your ptessure plate to Tennessee Clutch for a rebuild. They are quick and fair on pricing. Not sure how that would work with Caniadian customs. They can also supply you with a fresh disc.

Is your mystery piece a rod bolt?

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Thanks Don for the additional pictures and info. There are several clutch and brake shops around here that I will check out for grinding my clutch — shipping that stuff to TN and back would be pretty expensive even if the work was free!

Not too much progress on the engine last couple days, been doing house stuff and getting my new tires studded (interesting process, will post info and pictures soon).

Cylinder head is warped 0.009" in the centre, block is near dead flat with a 0.0015 feeler reluctant to go under the straightedge. I was planning a 0.050" head shave anyway so the warpage is no real concern. From past info posted, the 0.050 should be both safe and worth doing. Comments?

The water distribution tube is brass and as far as I can see (not very), in good shape and not corroded. I read of the considerable difficulty many have had removing this item and am considering just leaving this one in as is. Comments?

Several years ago I attended a garage sale and bought a 3/4" drive socket set from a retired HD mechanic. Never touched the thing until tonight when I dug it out and found, to my delight, a 1-3/4" socket just right for the crank pulley nut. Right on. The pulley itself looks like it wants to come off with a three-leg puller — is this right?

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Pull the tube. You want to get all the gunk out of it and the rest of the water jacket. There should be 2 bolt holes in the pulley for a puller. Don't pull it by the outside.

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Guest P15-D24

and all welch plugs to fully clean the water jacket. Also need to pull all the oil gallery plugs so you can clean out the oil gallery. Their will be quite a bit of residue at the bottom of the water jacket.

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Chris, it will be worth the effort to pull the water distribution tube. I have always had good luck pulling them. The brass tubes seem to be much easier to pull than the steel ones. I have yet to see a steel one in a Canadian built engine. Last one I pulled was this summer in a '54 Dodge parts car and I got it out with a bent clothes hanger, a pair of vise grips, and a small hammer.

Pull it; you will be glad you did for the peace of mind if nothing else.

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I will suggest another idea for the tube. If main funtion is to direct coolant up to the area under the valve seats and to distribute that coolant as equally as possible from front to back. AS long as the slots in the top of the tube facing the valves are free and clear of rust and debris, (the picture looks amazingly clean) and you can get a wire all the way to the back of the tube, you should be good to go. If the tube wants to cooperate with being removed, I would leave it. If it appear clean and doesn't want to leave its cozy position, I would leave it.

The problem with the steel ones is that they rust and the slots get filled with rust, or other holes get opened up from corrosion, limiting the flow or diverting it unequally toward the valves. I believe someone posted here that they were having problems with removal, and out of frustration or in a moment of blind inspiration, drilled a hole into the passage at the rear of the engine and loosened the tube by inserting a steel rod through the hole and whacking with hammer dislodge it. When finished he taped the hole and put in a threaded plug to seal it.

I have no guess as to the origin of the mystery hardware.

I can comment on the .050 milling, as I did mine .010 off the block and .040 off the head. The machine shop fellow calculated an 8 to 1 CR give or take a point or two. and he said likely higher as the .030 overbore contributes a bit to the equation. With that increase I run 4 to 5 degrees of initial advance, and have plenty of power and no spark knock on 87 octane fuel. Maybe could crank a couple degrees more I wanted to run 89.

To find out nominal compression ratio, divide you compression gauge reading by 14.7 which is sea level atmospheric pressure. Mine run low of 125 psi and high of 130,

Which is roughly 8.4 to 1

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Ed, my intention is to keep the rust and whatever is left of the original paint on the engine to blend with the patina (lazy man's term for rust, dirt, grease, muck and assorted other corruption) of the rest of the car. So I will flush the block thoroughly once all the openings are open, but no hot tanking.

I had been mentally working out the details of some exotic homemade water distribution tube puller, but Robert ruined that idea for me... a bent coat hanger, vice grips, a small hammer and five minutes of tapping did the trick nicely. The tube was pretty much clean as a whistle all the way to the end.

The crank pulley came off easily with my puller homemade from a couple carriage bolts and a bit of old bedframe. This is the newest engine I have ever worked on, and the first for which the crank pulley is more than just a simple pulley.

I'm at the timing gears and chain now. There is 11/16" total play in the chain and a bit of wear showing on the cam gear. While I cannot find any specs on acceptable war in my manual, it looks to me like the whole works of chains and two gears probably wants to be replaced. Comments?

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Gotta love those brass tubes. I have no idea why Chrysler ever used steel ones. Chris, sorry to ruin any Rube-Goldberg contraption type tube puller you were going to devise. As mentioned, I have always had good luck pulling the brass tubes with very basic tools.

You should be able to put the timing chain on its side and have virtually no sag in it. As you have everything apart I would certainly replace at least the chain, and the gears if they are showing signs of wear. Easy to do it now rather than later.

Also, I hope you kept track of the bolts that hold the timing chain cover on. I believe some have little lead washers on them as those particular bolts go into the water jacket. If you use the search function you should find a thread on this that an old member (Normspeed) did who had that problem. I have also found that anti-seize works well to prevent any leakage. This is true of headbolts and manifold bolts as well. I found the thread http://www430.pair.com/p15d24/mopar_forum/showthread.php?p=32236&highlight=timing+cover#post32236 Scroll about half way down.

Keep up the good work and keep posting those pictures!

Edited by RobertKB
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Holy cow are you going to be exited when you get that engine back together. With your low compression, and relaxed valve timing that has been exhibited by that engine it was probably only making half the power is should be.

Between upped compression and back to factory spec valve timing you will be thinking you have a rocket ship under you.

In the last picture with the timing gears and chain, look closly at the short little tube behind the assembly. It provided the oil for the gears and chain. It appears to be pratially obstructed. Make sure you keep the tube, assuring that it and it's feed are clear and free to provide the proper flow of oil to the timing assembly.

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Gotta love those brass tubes. I have no idea why Chrysler ever used steel ones. Chris, sorry to ruin any Rube-Goldberg contraption type tube puller you were going to devise. As mentioned, I have always had good luck pulling the brass tubes with very basic tools.

You should be able to put the timing chain on its side and have virtually no sag in it. As you have everything apart I would certainly replace at least the chain, and the gears if they are showing signs of wear. Easy to do it now rather than later.

Also, I hope you kept track of the bolts that hold the timing chain cover on. I believe some have little lead washers on them as those particular bolts go into the water jacket. If you use the search function you should find a thread on this that an old member (Normspeed) did who had that problem. I have also found that anti-seize works well to prevent any leakage. This is true of headbolts and manifold bolts as well. I found the thread http://www430.pair.com/p15d24/mopar_forum/showthread.php?p=32236&highlight=timing+cover#post32236 Scroll about half way down.

Keep up the good work and keep posting those pictures!

I have never seen a flattie uphere without the brass water distribution tube. I have gone through about 7 engines, all brass tubes to date....

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