New Engine Troubleshooting- Continued
Posting Guru
Joined: Jul 2006
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Originally Posted by Kwikkordead
On the older mechanical diesels you loosen the pump and move it like a gasser distributor.
If the rods were short wouldn't this show up as low compression. Try the cps replacement easier than pulling the engine. Might or might not work but worth the effort. Jim
Last edited by vettdvr; May 12, 2007 at 12:47 PM.
Fleet Owner
Joined: Jun 2004
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From: Rio Rico, AZ.
Originally Posted by vettdvr
on a 7.3 2000 would it be the same way?
If the rods were short wouldn't this show up as low compression. Try the cps replacement easier than pulling the engine. Might or might not work but worth the effort. Jim
If the rods were short wouldn't this show up as low compression. Try the cps replacement easier than pulling the engine. Might or might not work but worth the effort. Jim
The Bosch systems that are on VW, Mercedes, Cummins, they are all like that. You set the timing with a dial indicator that takes measurements of how far the plunger has moved from the bottom of it's stroke.
And yes short rods will really drop the compression as KennedyFord has already explained via the short pistons.
Bottom line if the piston crown doesn't come up as high as it used to for whatever reason, the combustion chamber is suddenly a lot larger than it used to be and the air doesn't have to fit into such a small space anymore, so the compression readings drop.
Fleet Owner
Joined: Jun 2004
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From: Rio Rico, AZ.
Ok, I just pulled my CPS and it's just like the diagram that Alan provided. If it's 180 out then there is a blank space in the pickup wheel on the camshaft. Or that may be the TDC reference. On one part the divider is dead on in the center of the hole and on the other one the blank area is dead on in the center of the hole.
For those of you that want to see for yourself, have a spare o-ring handy. The Ford o-ring swells up and it will be impossible to get the CPS back in without a new o-ring.
For those of you that want to see for yourself, have a spare o-ring handy. The Ford o-ring swells up and it will be impossible to get the CPS back in without a new o-ring.
Fleet Owner
Joined: Jun 2004
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From: Rio Rico, AZ.
Originally Posted by FN74
Dan- The super quiet idle is actually not near as prominent since I replaced the Head Gaskets. But I do know I have to wait for the glow plugs to cycle before it will start, even when it is 55 out, and it smokes a fair amount until warmed up. I KNOW for a fact that the Cometic head gaskets were leaking under load. Everytime I got into the throttle hard, it would pressurize my coolant system and push antifreeze out the refill bottle. But ONLY under heavy throttle. And it didn't do it in Denver, or high altitudes. So I replaced the stainless steel Cometic Head gaskets with stock ones. And it seemed to run better for a day and a half, although I never pushed it at all. My boost was without a doubt more responsive. So after a couple warm up periods, I got into it and nothing. There was no sudden change, but the truck just didn't respond. And now I have a lot of the same symptoms as before with the known leaking head gaskets.
However I know stock HG don't just ooze, they seal or they don't. The thing idles fine, drives good, doesn't miss, Rotational Velocity was basically 0 on all cylinders. Doesn't leak antifreeze anymore. Had I rebuilt a stock truck, one would never know anything is wrong.
Another thought that had crossed my mind was I know long block was rebuilt using Mahle Pistons which are apprently a little shorter to compensate for decking. But then if that was the case, my compression should show up low, not at 400 wouldn't it?
However I know stock HG don't just ooze, they seal or they don't. The thing idles fine, drives good, doesn't miss, Rotational Velocity was basically 0 on all cylinders. Doesn't leak antifreeze anymore. Had I rebuilt a stock truck, one would never know anything is wrong.
Another thought that had crossed my mind was I know long block was rebuilt using Mahle Pistons which are apprently a little shorter to compensate for decking. But then if that was the case, my compression should show up low, not at 400 wouldn't it?
Fleet Mechanic
Joined: May 2005
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From: Chattanooga
We need numbers. .015 is the first start of all the thickness of the head gasket for race engines I worked with bringing the head lower to the deck and pistons. If the block and heads were decked for performance we would have high compression with the equal cut to the top of the pistons. Decked for cleanup not an issue because were only talking thousands. The gasket makes up for any differences. There would have to be a significant change between the stock and other head gaskets to lower that compression ratio. Pie R squared x say .015 x 8....I dont think that would be enouph to give problems. Same issues of not much power with both scenarios.
a. What is stock compression tests and compression ratios?
b. How much was decked from your block
c. Is this your block or a spare that may have a crack in the block somewhere or heads?
d. What is stock thickness of normal pistons and replacements as well as the head gaskets?
I believe in my heart that it is still a fuel timing or timing issue itself.
a. What is stock compression tests and compression ratios?
b. How much was decked from your block
c. Is this your block or a spare that may have a crack in the block somewhere or heads?
d. What is stock thickness of normal pistons and replacements as well as the head gaskets?
I believe in my heart that it is still a fuel timing or timing issue itself.
Post Fiend
Joined: Jun 2006
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From: Central, Al
Couple of notes from the manual
Inspection
NOTE: Cylinder heads used on the diesel engine cannot be resurfaced. Install a new cylinder head if it is cracked or warped.
Inspect the cylinder head for cracks, burned valves or seats and scratched or marred gasket mating surface.
NOTE: If it is suspected that the cylinder head has been resurfaced, using a suitable micrometer, measure the cylinder head thickness at four different points.
Measure the cylinder head thickness. If the deck-to-deck measurements are not within specifications, replace the cylinder head
Spec is 129.41mm - 129.67mm (5.095" - 5.105")
Inspection
NOTE: Cylinder heads used on the diesel engine cannot be resurfaced. Install a new cylinder head if it is cracked or warped.
Inspect the cylinder head for cracks, burned valves or seats and scratched or marred gasket mating surface.
NOTE: If it is suspected that the cylinder head has been resurfaced, using a suitable micrometer, measure the cylinder head thickness at four different points.
Measure the cylinder head thickness. If the deck-to-deck measurements are not within specifications, replace the cylinder head
Spec is 129.41mm - 129.67mm (5.095" - 5.105")
Post Fiend
Joined: Feb 2006
Posts: 11,892
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From: Middle Tennessee
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Postmaster
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From: Fulltime RVer
I'm sorry that this saga is causing you so much grief, but it reminds me of a medical mystery diagnosis show I watch on Sat TV where every time a new "specialist" has a seemingly correct diagnosis for the patient's ailment, new tests come back negative and the mystery continues.
If we're starting to consider effects down to the 0.001's of an inch, are any of the following possible contributors? (1) Is it possible that the stock hydraulic lifters are too weak for the "Comp Cam" valve springs which I'm assuming are considerably stiffer than stock? (2) Valve lash too loose might cause an ever so slight reduction of air flow in during exhaust/intake stroke or too tight a slight compression loss during compression/power stroke due to excessive overlap.
What's the procedure for adjusting valve lash. On my old 56 and 58 Chevy's, I recall running the engine with the valve covers off and adjusting the rockers to get the hydraulic lifters centered in their working range using a feeler gauge. Even with solid lifters on my race engines I always did a double check with the engine running. So how do you make sure the valve train is working ok on a diesel since you can't check it with the engine running?
If we're starting to consider effects down to the 0.001's of an inch, are any of the following possible contributors? (1) Is it possible that the stock hydraulic lifters are too weak for the "Comp Cam" valve springs which I'm assuming are considerably stiffer than stock? (2) Valve lash too loose might cause an ever so slight reduction of air flow in during exhaust/intake stroke or too tight a slight compression loss during compression/power stroke due to excessive overlap.
What's the procedure for adjusting valve lash. On my old 56 and 58 Chevy's, I recall running the engine with the valve covers off and adjusting the rockers to get the hydraulic lifters centered in their working range using a feeler gauge. Even with solid lifters on my race engines I always did a double check with the engine running. So how do you make sure the valve train is working ok on a diesel since you can't check it with the engine running?
Fleet Owner
Joined: Jun 2004
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From: Rio Rico, AZ.
Originally Posted by vettdvr
Left field thought,, have you confirmed the exhaust is clear?
All this discussion and work and it boils down to a neighborhood prankster jamming a rock up the tailpipe.
Posting Guru
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Originally Posted by Kwikkordead
HAHAHAHAHAHA, it that were the case it would be one for FTE history!!!!
All this discussion and work and it boils down to a neighborhood prankster jamming a rock up the tailpipe.
All this discussion and work and it boils down to a neighborhood prankster jamming a rock up the tailpipe.
I did have a cat. converter fail on a 79 Eldorado and have the same problem description.
Jim
Thread Starter
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Elder User
Joined: Oct 2006
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From: New York
Originally Posted by vettdvr
Left field thought,, have you confirmed the exhaust is clear?
. The longblock in question is the original from my 99. The engine was rebuilt with the original crank, rods, heads, valves. New Oil pump, bearings, seals, springs, pistons. I just talked with the engine builder and he said Everything was in really good shape so there was only minimal machine work needed. He only did a cleanup of the deck and heads, between .005 and .010. And the new Mahle pistons come cut .010 just for that reason. The current head gaskets are OEM stock head gaskets. When I had the heads off, there was no sign of any valve contact at all. Although there was an obvious carbon trail between 5 and 7 on the head, and now looking at the pictures, I can see where previously I had a blow out right out the side of the head. Take a look at #6, and the rust on the head between 6 and 8.
