how easy is it to change lifters on a 4.0 6 straight
03-23-2012 | 09:42 PM
#4
CF Veteran
Joined: Oct 2010
Posts: 2,150
Likes: 12
From: Ontario, Canada
Year: 1989 Laredo
Model: Cherokee
Engine: 4.0 L 6 Renix
Proceedure is excellent for replacing the rocker arms, and often that is the noise source, perhaps even and adjustment will suffice. The lifters will require the head removal, at that point if the lifters are pooched, then the cam must be in need of some love also. If youve gone this distance then what about the valsve springs, retainers, valve seats, etc. It can quickly snowball. Hve a good look at the rockers 1st, replace em if worn out. Set the valve lash with cylinder at TDC, rotate the pushrod with your fingers, tighten to remove play between rocker and pushrod, then 1 1/2 turns tighter.
03-23-2012 | 10:23 PM
#5
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
The rockers r held in place by bridges....1 bridge per pair of valves. The bridges get torqued to 21 lb/ ft, I believe. That's the adjustment/setting.....no spinning push rods and 1 1/2 turns of a nut after they stop spinning....just torque the bridges down.
03-24-2012 | 01:39 AM
#6
CF Veteran
Joined: May 2008
Posts: 3,018
Likes: 17
Year: 1988
Model: Cherokee
Engine: AMC242
Remove rocker arms
Remove cylinder head
Remove lifters
Install new lifters
Reinstall cylinder head
Reinstall rocker arms
Reinstall valve cover.
Sadly, the "Modern Era" AMC six never got a side access plate inbuilt - which is something I consider silly. Thus, the head must be removed to access the lifters for service.
How sure are you it's a lifter tap - have you undertaken any diagnosis to isolate or identify the noise? It never hurts to be sure - and a mechanic's stethoscope is both a cheap tool and a very useful tool!
If it does seem to be a tappet knock, I'd suggest flushing your oil first - most tappet knocks are caused by a buildup of sludge or varnish in the tappets, which interferes with the free action of the plunger. Ergo, something detergent enough to break the crud loose is helpful. Ideas that have worked for me before:
- Change the oil. Replace one quart of engine oil with one quart of Marvel Mystery Oil - it's good stuff! Run normally, drain while hot. Repeat PRN.
- Change the oil. Replace 1-2 quarts of engine oil with a like amount of automatic transmission fluid (Type F is more detergent than Dexron/Mercon, and will be more aggressive...) and run fairly hard for 500-1,000 miles and drain while hot. I don't suggest doing this twice on the run - automatic transmission fluid can be antagonistic to engine seals. (FYI - Type F also makes a good ersatz hand cleaner. Use the Type F to get the crud off, then use regular soap to get the Type F off.)
- Use a good engine flush - Berryman's B-12 Chemtool works, and I've heard good results from Seafoam and I think Lucas makes something that works fairly well - and follow the instructions on the can. (I usually do this sort of thing as a "maintenance flush" - I've noted the previous two methods tend to be more aggressive.)
NB: Whether or not you've got sludge or varnish buildup that's causing your tappet knock, you may have a leak "appear" after the flush. This would be because you've had a seal that was about to go out anyhow, but it had a buildup of sludge that helped to keep is sealed. Flushing the sludge out often brings these incipient leads to light - it merely accelerates notice of a failed/failing seal, it doesn't cause seal failure in and of itself. This is also common when switching to synthetic oils - which has started the "synthetics cause leaks" myth.
Considering the difficulty in replacing the liftes on the 6-242, I'd try a detergent first. For best effect, you should drain your oil as hot as you can stand it - it will carry more crud out that way.
03-24-2012 | 02:34 AM
#7
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 19
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
Was wondering if anyone has had any luck, thinking you could get a little berymans or something to run down a push-rod and puddle around the lifter. Overnight it might get into somewhere it could help.
Can't you put new lifters on a worn cam, but a new cam with worn lifters, bad idea?
Can't you put new lifters on a worn cam, but a new cam with worn lifters, bad idea?
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03-24-2012 | 08:35 AM
#8
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,565
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Remove valve cover
Remove rocker arms
Remove cylinder head
Remove lifters
Install new lifters
Reinstall cylinder head
Reinstall rocker arms
Reinstall valve cover.
Sadly, the "Modern Era" AMC six never got a side access plate inbuilt - which is something I consider silly. Thus, the head must be removed to access the lifters for service.
How sure are you it's a lifter tap - have you undertaken any diagnosis to isolate or identify the noise? It never hurts to be sure - and a mechanic's stethoscope is both a cheap tool and a very useful tool!
If it does seem to be a tappet knock, I'd suggest flushing your oil first - most tappet knocks are caused by a buildup of sludge or varnish in the tappets, which interferes with the free action of the plunger. Ergo, something detergent enough to break the crud loose is helpful. Ideas that have worked for me before:
- Change the oil. Replace one quart of engine oil with one quart of Marvel Mystery Oil - it's good stuff! Run normally, drain while hot. Repeat PRN.
- Change the oil. Replace 1-2 quarts of engine oil with a like amount of automatic transmission fluid (Type F is more detergent than Dexron/Mercon, and will be more aggressive...) and run fairly hard for 500-1,000 miles and drain while hot. I don't suggest doing this twice on the run - automatic transmission fluid can be antagonistic to engine seals. (FYI - Type F also makes a good ersatz hand cleaner. Use the Type F to get the crud off, then use regular soap to get the Type F off.)
- Use a good engine flush - Berryman's B-12 Chemtool works, and I've heard good results from Seafoam and I think Lucas makes something that works fairly well - and follow the instructions on the can. (I usually do this sort of thing as a "maintenance flush" - I've noted the previous two methods tend to be more aggressive.)
NB: Whether or not you've got sludge or varnish buildup that's causing your tappet knock, you may have a leak "appear" after the flush. This would be because you've had a seal that was about to go out anyhow, but it had a buildup of sludge that helped to keep is sealed. Flushing the sludge out often brings these incipient leads to light - it merely accelerates notice of a failed/failing seal, it doesn't cause seal failure in and of itself. This is also common when switching to synthetic oils - which has started the "synthetics cause leaks" myth.
Considering the difficulty in replacing the liftes on the 6-242, I'd try a detergent first. For best effect, you should drain your oil as hot as you can stand it - it will carry more crud out that way.
Remove rocker arms
Remove cylinder head
Remove lifters
Install new lifters
Reinstall cylinder head
Reinstall rocker arms
Reinstall valve cover.
Sadly, the "Modern Era" AMC six never got a side access plate inbuilt - which is something I consider silly. Thus, the head must be removed to access the lifters for service.
How sure are you it's a lifter tap - have you undertaken any diagnosis to isolate or identify the noise? It never hurts to be sure - and a mechanic's stethoscope is both a cheap tool and a very useful tool!
If it does seem to be a tappet knock, I'd suggest flushing your oil first - most tappet knocks are caused by a buildup of sludge or varnish in the tappets, which interferes with the free action of the plunger. Ergo, something detergent enough to break the crud loose is helpful. Ideas that have worked for me before:
- Change the oil. Replace one quart of engine oil with one quart of Marvel Mystery Oil - it's good stuff! Run normally, drain while hot. Repeat PRN.
- Change the oil. Replace 1-2 quarts of engine oil with a like amount of automatic transmission fluid (Type F is more detergent than Dexron/Mercon, and will be more aggressive...) and run fairly hard for 500-1,000 miles and drain while hot. I don't suggest doing this twice on the run - automatic transmission fluid can be antagonistic to engine seals. (FYI - Type F also makes a good ersatz hand cleaner. Use the Type F to get the crud off, then use regular soap to get the Type F off.)
- Use a good engine flush - Berryman's B-12 Chemtool works, and I've heard good results from Seafoam and I think Lucas makes something that works fairly well - and follow the instructions on the can. (I usually do this sort of thing as a "maintenance flush" - I've noted the previous two methods tend to be more aggressive.)
NB: Whether or not you've got sludge or varnish buildup that's causing your tappet knock, you may have a leak "appear" after the flush. This would be because you've had a seal that was about to go out anyhow, but it had a buildup of sludge that helped to keep is sealed. Flushing the sludge out often brings these incipient leads to light - it merely accelerates notice of a failed/failing seal, it doesn't cause seal failure in and of itself. This is also common when switching to synthetic oils - which has started the "synthetics cause leaks" myth.
Considering the difficulty in replacing the liftes on the 6-242, I'd try a detergent first. For best effect, you should drain your oil as hot as you can stand it - it will carry more crud out that way.
03-24-2012 | 11:04 PM
#9
CF Veteran
Joined: May 2008
Posts: 3,018
Likes: 17
Year: 1988
Model: Cherokee
Engine: AMC242
Was wondering if anyone has had any luck, thinking you could get a little berymans or something to run down a push-rod and puddle around the lifter. Overnight it might get into somewhere it could help.
Can't you put new lifters on a worn cam, but a new cam with worn lifters, bad idea?
Can't you put new lifters on a worn cam, but a new cam with worn lifters, bad idea?
New Tappets w/Used Cam = No trouble.
Used Tappets w/New Cam = Rapidly Wrecked Cam
Used Tappets w/Used Cam = No trouble (if lifters are on the same lobes they came off of.)
Used Tappets w/Used Cam = Wrecked Cam (if lifters are on different lobes than they were removed from.)
I've put new tappets on used cams often, and haven't had any trouble. As long as the camshaft itself isn't wiped out, you'll be fine - just follow normal run-in procedure.
03-24-2012 | 11:52 PM
#10
Thread Starter
Junior Member
Joined: Feb 2011
Posts: 51
Likes: 0
Year: 1994
Model: Cherokee
Engine: straight 6 4.0 L
Originally Posted by 5-90
Remove valve cover
Remove rocker arms
Remove cylinder head
Remove lifters
Install new lifters
Reinstall cylinder head
Reinstall rocker arms
Reinstall valve cover.
Sadly, the "Modern Era" AMC six never got a side access plate inbuilt - which is something I consider silly. Thus, the head must be removed to access the lifters for service.
How sure are you it's a lifter tap - have you undertaken any diagnosis to isolate or identify the noise? It never hurts to be sure - and a mechanic's stethoscope is both a cheap tool and a very useful tool!
If it does seem to be a tappet knock, I'd suggest flushing your oil first - most tappet knocks are caused by a buildup of sludge or varnish in the tappets, which interferes with the free action of the plunger. Ergo, something detergent enough to break the crud loose is helpful. Ideas that have worked for me before:
- Change the oil. Replace one quart of engine oil with one quart of Marvel Mystery Oil - it's good stuff! Run normally, drain while hot. Repeat PRN.
- Change the oil. Replace 1-2 quarts of engine oil with a like amount of automatic transmission fluid (Type F is more detergent than Dexron/Mercon, and will be more aggressive...) and run fairly hard for 500-1,000 miles and drain while hot. I don't suggest doing this twice on the run - automatic transmission fluid can be antagonistic to engine seals. (FYI - Type F also makes a good ersatz hand cleaner. Use the Type F to get the crud off, then use regular soap to get the Type F off.)
- Use a good engine flush - Berryman's B-12 Chemtool works, and I've heard good results from Seafoam and I think Lucas makes something that works fairly well - and follow the instructions on the can. (I usually do this sort of thing as a "maintenance flush" - I've noted the previous two methods tend to be more aggressive.)
NB: Whether or not you've got sludge or varnish buildup that's causing your tappet knock, you may have a leak "appear" after the flush. This would be because you've had a seal that was about to go out anyhow, but it had a buildup of sludge that helped to keep is sealed. Flushing the sludge out often brings these incipient leads to light - it merely accelerates notice of a failed/failing seal, it doesn't cause seal failure in and of itself. This is also common when switching to synthetic oils - which has started the "synthetics cause leaks" myth.
Considering the difficulty in replacing the liftes on the 6-242, I'd try a detergent first. For best effect, you should drain your oil as hot as you can stand it - it will carry more crud out that way.
03-25-2012 | 12:48 AM
#11
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 19
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
Thanks again for great info ^. I guess used, concave lifters riding on a nice flat new cam is a bad idea. The other way around, not so bad.
And it will "cycle" like that? Do you have a gauge or a light for your oil pressure?
And it will "cycle" like that? Do you have a gauge or a light for your oil pressure?
03-25-2012 | 03:55 AM
#12
CF Veteran
Joined: May 2008
Posts: 3,018
Likes: 17
Year: 1988
Model: Cherokee
Engine: AMC242
(The very few times I've seen concave tappet feet, it's been coincidental to other major problems - usually caused either by oiling or by bad sludge buildup. The four cases of hollowed-out tappet feet I've seen in the last thirty-odd years were accompanied by the use of paraffin-base oils - Pennzoil in three cases, old-formula Quaker State in the other. Paraffin in oil has similar effects on your engine as triglycerides do in you - artheriosclerosis, blockage, loss of circulation, and other crap.
(Why don't I like Pennzoil? I used to make candles out of the sludge, and I'd actually gotten engines wanting overhauls that, when I tried to drain them, I'd pull the plug and nothing came out! I ended up taking a bit of copper rod and making something like a "soccer-ball inflator" needle to push in through the sludge to drain the oil. Yech.
As a result, I won't even use two-stroke oil made by Pennzoil, and I won't even use the stuff in my lawnmower...)
03-25-2012 | 08:07 AM
#13
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,565
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Well I have listened to the tick and I prurty sure it is coming from the valve cover I have changed the oil and put some additives in it and still the tick just comes and goes and starts off not that loud and as it ticks it gets louder and louder untilled it stops for like 10 min and then repeats? Idk what to do anymore
03-25-2012 | 09:42 AM
#14
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 19
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5