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idlebumski
Dodge Dakota
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6/15/2003
12:31:35
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 Subject: How do lifters work?
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Message:
I have a 2000 CC R/T which has just had the
heads redone due to couple of cracks and
burnt valves. The heads were ground maybe
slightly too much, which has altered geometry
of valve train and (I think) weakened already
weak lifters so that my truck runs perfect when
cold but crap when hot. My question to
anybody in the know is: How much play do the
lifters have and are they designed to
compress or expand once the oil is hot?
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idlebumski
Dodge Dakota
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6/15/2003
21:34:55
| RE: How do lifters work?
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Message:
Hello? Surely somebody here knows how
these things work...
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gg
Dodge Dakota
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6/16/2003
02:29:24
| RE: How do lifters work?
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Message:
mopar book sez you may need adjustable push rods,because of the big head shave
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GR
Dodge Dakota
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6/16/2003
08:35:16
| RE: How do lifters work?
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Message:
Lifters are mechanical/hydraulic followers of the camshaft lobe, and lift the valve through the cycle engineered into the cam. The lifter is filled with engine oil through small holes in corresponding galleries of the block and the lifter and kept filled by engine oil pressure. If you have had the heads shaved or milled more than a few thousands, the valves may be held fractionally open, thereby causing loss of compression. Try this: Take off your valve covers. Start the engine. Let it idle. Using a rachet with the proper size socket, back off (loosen) the nut in the center of the rocker arm until the valve starts to tap, then tighten it approx. one-half turn. Do it on all valves, both intake and exhaust.
This procedure assumes that you have adjustable rocker arms. Otherwise you'll have to buy adjustable push rods.
Associated problems: contaminated/obstructed oil galleries in the block; mismatching of the intake manifold and block ports due to the shaving; lifters that have been contaminated by engine debris.
Hope you solve your problem(s).
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idlebumski
Dodge Dakota
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6/16/2003
10:23:18
| RE: How do lifters work?
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Message:
Hey GR, that was very informative, thanks.
Before you take off, could I just ask one more
thing so that I know what I'm talking about
when taking it back to these guys who did it
and claim it runs fine: It runs perfect cold, but
once hot, there's an ugly banging sound at
idle (about 170BPM) somewhere down under
valve covers/intake on drivers side at or near
cylinder 5 which can be heard with either hood
up, or when closed from under wheel arches.
Also when hot, it missfires badly at low
revs/low throttle and almost sounds like it will
cease running the more it is driven. Based on
your post above, is it possible there's a valve
already banging against the seat and not
opening wide enough, along with others
which are not closing properly and opening
too wide?
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GR
Dodge Dakota
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6/17/2003
07:44:24
| RE: How do lifters work?
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Message:
As you well know, materials expand when hot. If it runs fine when cold, it sounds like expansion caused noise. If you're mechanically inclined, remove the valve cover and look in the area where the noise comes from (perhaps a binding valve spring/perhaps loss of lubrication to one lifter or the entire valve train). While the engine is idling, taking a two foot, round wooden dowell and placing it near or on the suspected site and holding it to your ear might further narrow the problem area (the wood transmits engine noises, but pls. be careful here). You might also consider another mechanic's opinion, someone whose opinion you trust and respect. Seeing and hearing it help to define the problem and will give you additional information to take to the people who did the work.
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rtdkota
R/T
6/17/2003
11:06:44
| RE: How do lifters work?
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Message:
Hey JP-- I got your message, I have been terribly busy trying to get ready for racing at Barona this Friday evening.
I spoke to the guys at the shop at length-- sounds like they are covering all the bases-- there's a few things they are going to check re: the miss and or slugishness...
The noise may be a header leak or crack... something to consider. I was trying to head up your way this weekend, but it's my son's 2nd B-day on Saturday-- so that's out.
I'll be available for a little bit on Friday from noon-3 pm or so-- before I go to Barona if you want to stop by.
Sam
www.socaldakota.com
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