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idlebumski
Dodge Dakota
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4/13/2003
15:26:59
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 Subject: How do burnt valves happen?
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Message:
Hello everybody.
I've not posted here in ages but need your
advice: Ever since I bought my truck (2000 C/C
with 30k miles) it always felt like something
was off. Now, with 50k miles I could stand it
no longer and had it compression tested.
Came back with # 4 and 8 cylinders way down
to 100 when they should be around 125-130.
Also, # 2 is getting down there at 110. Dan
Cragin (the Viper guy here in LA) told me he
blew air into chambers and could hear it
leaking out exhaust valves so suggests a
valve job. Well, I'm happy to now know it wasn't
my imagination but wonder, how does this
happen? FYI: When purchased, only mod was
horrible glasspack muffler. Now, it has PPH
headers, better muffler, and, unfortunately, an
Airaid intake. Anybody have any ideas?
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brianman
Dodge Dakota
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4/14/2003
03:17:04
| RE: How do burnt valves happen?
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Message:
sometimes you could have carbon on the seats and that can hold the valve open long enough. sometimes stem seals are to tight and the guides and valves run dry and eventually hold open. it really doesnt have to be open for too long before the valve burns. i have seen propane motors do this lots as the fuel is very dry and offers no lubricity.
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Beevis
Dodge Dakota
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4/14/2003
08:58:28
|  RE: How do burnt valves happen?
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Message:
he said, lubricity, ah huh huh
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RED97KOTA
Dodge Dakota
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4/14/2003
10:24:47
| RE: How do burnt valves happen?
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Message:
Burned valves happen because a small spot of wear or "pit" first appears on the exhaust valve and the escaping high velocity gasses slowly eat away at the valve. (burned intake valves are rare)The seat is harder than the valve so anything that gets embedded usually gets in the valve face. A burned valve is very rare in a vehicle with 50K miles much less multiple valves with this problem. Lean/dry fuel mixtures will aggrevate the problem but this should not be a concern in a modern computer managed engine. A much more likely problem is carbon buildup around the valve due to poor fuel quality or some other issue. Use a good carbon cleaner and see if that helps. We have over 2,000 vehicles in our fleet and I can count on my fingers the number of burned valves I have seen in the last few years on vehicles with less than 120K miles. And none of those had more than one. We see more carbon buildup, cracked heads and leaky head gaskets than burned valves. Re-check your compression to eliminate any error and do a good leak down test to pinpoint the leak if the carbon cleaner does not help.
From my experience....your results may vary....
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Backyard Tech
Dodge Dakota
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4/14/2003
10:52:35
| RE: How do burnt valves happen?
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Message:
One method to thoroughly clean all internals is to WHILE THE ENGINE IS RUNNING pour the entire contents bit by bit of a quart of transmission fluid down the intake.
Don't let it stall preferrably just keep up the throttle to keep it running.
Yes this will pour out jet white smoke out the exhaust like you have never seen before, however this is an excellent way to clean and lubricate the internals and it is absolutely harmless.
Your neighbours may very well shoot you or call the fire department when they see the smoke however.
Anyway it works!
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idlebumski
Dodge Dakota
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4/14/2003
11:28:45
| RE: How do burnt valves happen?
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Message:
Thanks for those last two responses guys, they were very helpful. Living in the middle of Los Angeles, I'm trying to think of a place I could try the pouring down trans fluid into the intake manifold trick, without causing a scene. I too am perplexed at what I thought should be a motor that would go forever showing signs of crapping out already. Is it possible to purge the carbon buildup by buying some type of cleaner and taking it for a hard drive one night (being in LA, it hardly ever gets it's legs stretched anymore). And if it is a cracked head, how could this come about?
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Dakaty
GenIII
4/14/2003
14:01:31
| RE: How do burnt valves happen?
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Message:
Valvoline makes a powerful "Once a year" carbon cleaner. It costs about $10.00. I have used it as "preventative medicine".
According to their pictures, it really cleans up the valves, piston and combustion chamber.
It might be worth a try.
PS. Valvoline also make a cheaper additive. Don't get it. Get the good one.
14.63 @ 91.8
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Chris
Dodge Dakota
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4/14/2003
14:20:16
| RE: How do burnt valves happen?
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Message:
I have heard that jsut misting water into the intake does this as well, I know i have had positive results doing this...
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RED97KOTA
Dodge Dakota
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4/14/2003
18:13:14
| RE: How do burnt valves happen?
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Don't do the water thing, too much and bad things happen....We use a product from G/M (sorry bout that guys)I think its part number is X66?? There is also a product available at marine stores and some NAPA stores called Seafoam which is also an excellent carbon cleaner, both smoke but not as bad as the trans fluid and are more effective.
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idlebumski
Dodge Dakota
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4/14/2003
19:01:09
| RE: How do burnt valves happen?
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Message:
OK. Buying the good Valvoline carbon cleaner
is smart, before pulling the motor to bits. This
weekend I am going up into the mountains,
being a nice long drive uphill, so will pour the
stuff in before heading off. Is the smoke factor
going to embarrase me?
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toddmrfixit
Dodge Dakota
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4/14/2003
21:20:16
| RE: How do burnt valves happen?
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Message:
burnt valves on 318 with low miles are not all that uncommon. i work at a repair shop and in the last year alone i destinctly remember a durango with 47,000 on the clock that had a burnt ex valve and another on the way. and a grand cherokee that had 68,000 with a burnt valve.they stuck out from the crowd of cars i work on because i was shocked to find that being the problem with such low miles and all.just my 2 cents
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handi2
GenIII
4/14/2003
21:25:30
| RE: How do burnt valves happen?
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Message:
Use the Transmission Fluid method as posted above. It works wonders. We did this in the 60's and it works.
Be prepared for the largest smoke plume you have ever seen.
2002 Quad Cab SLT Plus 4.7 Every Available Option
Bed Rug/Access Tonnoue Cover/Roadmaster Suspension/HO Cams
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paysonbadboy
Dodge Dakota
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4/14/2003
23:03:11
| RE: How do burnt valves happen?
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Message:
I agree.
Tranny fluid works great.
And makes one hell of a smoke cloud.
I have lots of experience using tranny fluid in the intake. Old timers swear that it cleans carbon excellently. But what I used to do is booby-trap my budies vehicles by pulling off the large vacuum hose for the brake booster and filling it up with tranny fluid. It causes your buddies (or enimies) car to smoke for miles and miles before it sucks all that out with the slow rate that it does! Plus it doesn't foul the plus like motor oil does. Whenever I had someone angry with me, my first line of defense was the claim of "cleaning the carbon from his valves and how he should be thankful"!
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RED97KOTA
Dodge Dakota
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4/15/2003
08:24:29
| RE: How do burnt valves happen?
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Message:
Again, I would caution against the trans fluid route, true trans fluid has a lot of detergent in it but it can also damage the converter by overwhelming it and causing excessive buildup which can cause a failed emissions test or the downstream o2 sensor will cause the check engine light to come on because of reduced efficiency of the converter. Use a good carbon cleaner thats the right product designed for the job and your risk is minimal for problems. I disagree that burnt valves are "common" on the 5.2L/318. We have 100's of these in our fleet with millions of total miles and do not see any head problems that stand out from other vehicles we have. I went back and scanned our work orders for the last year (this is not hard for us as each particular job ie:head removal is coded and we can bring it up in a matter of seconds) and reviewed the information. We had 2 instances of head removal, one on a 97 Ram 5.2L (92K) and the other was a 99 Van 5.2L (49K) in the first instance the valve was burned on #7 and the reason was noted to be excessive carbon buildup. In the second it was #4 that was burned (slightly) and the valve seat and head were cracked. (Previous w/o showed overheating as this was a prisoner transport van)
From my experience....Your results may vary.....
Good luck and keep us posted....
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j
GenIII
4/15/2003
18:45:59
| RE: How do burnt valves happen?
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Where is Dan Cragin's shop located?
2000 4.7 CC auto, clear corners, Magnaflow catback, Kenne Bell s/c.
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idlebumski
Dodge Dakota
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4/15/2003
19:18:52
| RE: How do burnt valves happen?
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I see from your profile you are in Torrance, CA. I looked long and hard for a guy here in Los Angeles who knew what he was doing with Dodges and didn't work at a rip-off dealership. One night while dyno-testing the R/T in Gardena, this guy pulls up in a tricked out Viper and after being introduced to him, it turns out he is the guy. His shop is in Culver City, sort of near Robertson and the 10. His address: 3370 S. Livonia, CA 90034 and number: 310-841-6996. Talk to him. It's fast Dodges only down there!
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j
GenIII
4/15/2003
20:33:37
| RE: How do burnt valves happen?
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Message:
Thanks for the info.
2000 4.7 CC auto, clear corners, Magnaflow catback, Kenne Bell s/c.
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