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pete
Dodge Dakota
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1/05/2010
12:02:50
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 Subject: RE: New cam mileage
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Tell me with 97,000 + in truck this has happen since I am the original owner since new and maintained properly ? and I don't have time to lay my truck up when its my daily driver and cannot drive wifes car and to do a cam swap or a cylinder head check for cracks , again not to be a smar!ass where does one get the time specially in the winter?
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Behaley
Dodge Dakota
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1/05/2010
20:10:34
| RE: New cam mileage
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I always thought winter was a better time to work on things because its too dark, cold and snow covered to do anything worthwhile outside. Of course, I also live 20 miles from the nearest town so a night live is almost non-existent. There are some simple things to do that don't take a lot of time to help diagnose possible problems. A compression check is probably the fastest and most valuable. A standard pressure compression check will reveal big problems--blow head gasket, big head cracks, really bad valves or rings, etc. This should take about 30mins. A differential compression check is much more revealing, but is difficult to do on an automotive engine. If I had to guess, if you haven't changed your timing chain in the last 100k miles, I would expect it to be very sloppy. Mine was stretched at least and inch and was supposed to only have 120k miles on it (not first owner). IF you don't have a tensioner on the timing chain (check with dealer or any other useful source), this can be roughly checked by having someone watch the distributor rotor while you rotate the crankshaft forward and backwards. Rotate the crank backwards slowly until the rotor just starts to move. Make a not of the crank position (wrench angle, alignment marks on crank pulley and something else, etc.) Then rotate the crank forward slowly until the rotor just starts to move the other way. If there is more than 1/2inch of movement, you probably have a worn chain. Mine moved about 30 degrees or 1.5inches. Either one of these can be done in less than an hour with anyone's help. These suggestions are assuming you have done the more usual small fixes--plug wires, plugs, cap, rotor, air filter, injector cleaning service, fuel filter, etc. As far as the crack head, I smelled anti-freeze in the exhaust and under the hood.
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pete
Dodge Dakota
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1/05/2010
23:20:26
| RE: New cam mileage
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Yes I have done heavy repairs in my days working in the service garage as a mechanic but long gone since owner closed doors.Its strange how you mention antifreeze smell I did have a heater hose leaking not thinking else, repaired it went bout my business than a week later did my tuneup didn't notice anything on plugs between 2&4 like you were saying as far as timing chain I thought these all had double rollers to eliminate slop? Truck runs good hardly uses any oil notice a little oil film in the belly pan.I could babble more leave it that
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Behaley
Dodge Dakota
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1/06/2010
19:46:54
| RE: New cam mileage
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The factory original timing chain is a silent type, not a roller. Everyone is replacing them with roller types because of the added durability. Even those will stretch eventually, just not as much. After seeing how much difference valve timing can have on performance and mileage, I am going to make sure it stays correct. I don't know why, but my new stock replacement cam was off by about 6 degrees retarded with the marks aligned correctly. This made the truck totally gutless and get 14-15mpg. That is the same thing that will happen when the chain stretches. While adjusting the valve timing without offset cam keys, I discovered that being one tooth off on the crank changes things by about 15 degrees and one tooth off on the cam changes things by about 30 degrees. The truck ran great with the timing retarded, but it just didn't have much power. This would be something that would develop so slowly that you probably wouldn't notice the loss of power over time, especially if you only drive in in town as lower speeds or short distances.
As far as the anti-freeze smell, I didn't have any leaks anywhere, could smell it in the exhaust and engine bay, and was slowly loosing coolant all the time, and I didn't have antifreeze on any of the plugs.
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pete
Dodge Dakota
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1/07/2010
11:31:53
| RE: New cam mileage
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After reading posts here there everyone was blaming O2's,leaky belly pan gaskets and now you advice timing retarded and sloppy timing chain,your advice bout timing makes me think some, I didn't think of the this considering the PCM should be adjusting your timing, and no PCM can adjust for wear and tear on any given motor its up to us determine the cause? I going to check into your timing suggestion will have to round up some tools to properly do this if I decide to tackle it.
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Behaley
Dodge Dakota
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1/07/2010
20:38:29
| RE: New cam mileage
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All the PCM does on our trucks is adjust injector timing, duration, ignition timing based on input signals from various sensors and ERG systems if they have them, to obtain the most optimum fuel burn for emissions purposes first and performance second. In general, it is assumed that optimum fuel burn will give optimum performance and the lowest emissions. It doesn't adjust valve timing. It simply reacts the air coming in and the oxygen going out. So if things like air filters plug, valves open different than designed, cam sensors get out of calibration with the actual cam position, individual injectors have bad spray patterns, spark plugs start getting bad spark patterns, or any mechanical wear, the PCM doesn't directly know or care, it just adjusts things for what air is actually coming in and what oxygen is going out. The controlling program was probably designed based on a blue print engine, and nation wide average environmental expectations. This usually works about as well as "one size fits most" situations--almost never perfect. Just like "one size fits most," too big or too small is a matter of opinion. The O2 is the only sensor it has to measure the result of the ignition and fuel outputs. I know people fear math, but the overly simplified basic idea is " A + B = constant." Consider "A" the ignition and fuel outputs, and "B" the O2 sensor reading. If "B" is too high, "A" must be lowered to maintain the constant.
Because it is much more complex and some of that complexity is dependent on personal opinions and fuzzy lines on graphs, aftermarket everything exists to improve the original systems. The question always comes up of "If its so good, why didn't the factor do it?" The simple answer is that is was not cost effective for them. But that is a whole other discussion.
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pete
Dodge Dakota
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1/08/2010
12:32:42
|  RE: New cam mileage
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Did you get this info from AA1 Car ? there's article on timing chain update almost word for word as you posted
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Behaley
Dodge Dakota
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1/09/2010
10:13:30
| RE: New cam mileage
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No, I've never heard of AA1 car. The info I gave is mostly from personal experience (10yrs aircraft mechanic) and professional knowledge as a Mechanical Engineer. I don't know all the specific little details and industry specific information because that is not my job. However, I fully understand combustion, mechanical, fluid flow, electrical and electronic system design theory and how all of them generally work and generally fail. Automotive Engineering is a complex subject, but all the general theories still have to apply.
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pete
Dodge Dakota
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1/10/2010
00:36:34
| RE: New cam mileage
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Message:
I was referencing as you posted about timing,there's website AA1.COM a site from Larry Carley (not here?) in one of the tabs(ENGINE DIAGNOSIS&REPAIR) talking about timing chain update your post relates to discussion to his, not knocking you by any means you,there and myself thinking along this discussion about where every ones mileage goes and blames on every sensor and gasket, etc. before they even consider wear and tear. I was attending college myself to become automotive engineer for this specialty but screwed around to much and drop out but now older and wiser would like to go back and get my degree completed again another babble story to talk about later...
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J and J Auto
GenII
1/21/2010
03:32:52
| RE: New cam mileage
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I replaced my chain and added the tensioner which
should always be added to the V6 because the cam
sits .050 closer to the crank at 80,000 miles
stock factory chain and gears
At 120,000 I changed the cam, with 40,000 on the
chain I removed it was as tight as the day I put
it in with the tensioner
With the new cam I used the same tensioner but
a cloyes true street roller .250 rollers, man
for a while I did not think I would be able to
get it in it was a tight fit
At that time I replaced the cam with a federal
mogal, new lifters, new push rods, new rockers
harland sharp 1.7's
I have about 4,000 on this new stuff now and my
mileage is about 1 to 1.5 better even in the cold
In the first 1000 miles I thought it was killing
my mpg but as soon as it seatted in it was better
now I am good to hit 500,000 miles
check out the Alpar website 1/2 million mile club
and you will see daks there with over 500,000 on
them
winter mileage is 19.5 20mpg on the back roads
22 highway
in the summer 24 25mpg 1995 4x4
Larry
J&J Auto
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pete
Dodge Dakota
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1/21/2010
16:56:53
| RE: New cam mileage
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why didn't these engineers think of this
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daddio
Dodge Dakota
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1/21/2010
17:04:16
| RE: New cam mileage
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dollars pete, dollars. save as much as possible so profit is as high as possible.
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pete
Dodge Dakota
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1/22/2010
19:09:46
| RE: New cam mileage
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Daddio everything evolves around $$$$ just think if the more dakota drivers there would be if these trucks got this kind of gas mileage and would of save a few dollars at the pump and the world a little more greener..... must I babble on
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