Carbon Fouling, Exhaust valve stems
Carbon Fouling, Exhaust valve stems
(OP)
Are there any miracle elixirs that will eventually remove carbon from an exhaust valve stem and prevent and further build up?
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Carbon Fouling, Exhaust valve stems
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Carbon Fouling, Exhaust valve stemsCarbon Fouling, Exhaust valve stems(OP)
Are there any miracle elixirs that will eventually remove carbon from an exhaust valve stem and prevent and further build up?
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RE: Carbon Fouling, Exhaust valve stems
RE: Carbon Fouling, Exhaust valve stems
RE: Carbon Fouling, Exhaust valve stems
RE: Carbon Fouling, Exhaust valve stems
I'd soak the exhaust manifold nuts with PB Blaster for a week, and then might try removing the ex manifolds (with an oxy-acetylene torch handy to coax the nuts free if they are reluctant ) to gain access to the valve stems via the open exhust ports. I'd fashion an aluminum or brass chisel, and chipp the carbon from the stems with many gentle taps with a small hammer.
To prevent the carbon's return for a while before overhauling the engine I'd clean the PCV system (and maybe boost its capacity), replace the stem seals (possible on the car with the heads on) and do a few short mileage oil changes and run synthetic oil with a 40 or 50 as the second viscosity number. And maybe even throw in a can of STP or something similar.
RE: Carbon Fouling, Exhaust valve stems
Carbon formation on valve stems as has already been stated are the results of poor engine condition. This may be exadurated by short trip low speed use and by diluted or light weight oil.
Real answer is to repair the engine.
Bandaids as mentioned above, such as downward oscilation of the right ankle to water injection will all work to remove the symptom
Regards
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RE: Carbon Fouling, Exhaust valve stems
The vehicle in question is a 1998 Range Rover 4.6HSE(P38) just turning 100K.This seems to be a common problem with this engine...I was hoping for an additive that would loose the carbon that apparently is binding some of the exhaust valve and giving me what feels like a miss. I'm the only one it bothers. I did the usual, plugs, cables, cap, rotor, fuel filter, air filters,and then finally a full round of injectors...looks like I'm R7Ring the heads next!
RE: Carbon Fouling, Exhaust valve stems
RE: Carbon Fouling, Exhaust valve stems
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If the chemical treatment does not work, a peak in the exhaust ports should reveal if stem build up is causing the sticking. AI'd expect a peak in the oil filler hole or at worst under a valve cover would reveal the strange thin brown gray build up of anti-freeze contamination.
RE: Carbon Fouling, Exhaust valve stems
RE: Carbon Fouling, Exhaust valve stems
RE: Carbon Fouling, Exhaust valve stems
RE: Carbon Fouling, Exhaust valve stems
It occurs to me that modern 2-stroke engines have flapper valves in the exhaust ports to modulate back-pressure for increased low-end torque, and certain 2-T oils contain a thermally stable detergent to keep them clean & from binding. May not be the best thing for your cat converter, but certainly sounds like what you're trying to accomplish . . .
RE: Carbon Fouling, Exhaust valve stems
Take care not to risk hydraulic lock by allowing water to flow or drain into the engine while it is not running.
It could be done cheaply with a windscreen washer kit, a toggle switch and a spring load push button switch, so that both switches had to be on for water to flow, thereby reducing risk of hydraulic lock.
Also water tank must be well below outlet nozzle so as to avoid possibility of syphon.
The water will clean the valves quite quickly, like in a minute or two at full load mid rpm on a dyno.
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Carbon Fouling, Exhaust valve stems
RE: Carbon Fouling, Exhaust valve stems