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Post by Deleted on May 14, 2020 20:49:14 GMT
My engine has started making a popping sound through the air intake (no smoke).
It's an isuzu 55. Its been a bit tappety, so the popping made me think intake valve. I've checked the clearances, and they were a bit out. I reset them, and the problem is not as bad as it was, but I still notice it a little on tick over.
Can I spray wd40 onto the valves from the top to see if it clears any crap on the seat?
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Post by Isambard Kingdom Brunel on May 14, 2020 21:20:34 GMT
No. It will do nothing. Decoke may be required with a valve reseating.
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Post by TonyDunkley on May 14, 2020 21:29:20 GMT
My engine has started making a popping sound through the air intake (no smoke). It's an isuzu 55. Its been a bit tappety, so the popping made me think intake valve. I've checked the clearances, and they were a bit out. I reset them, and the problem is not as bad as it was, but I still notice it a little on tick over. Can I spray wd40 onto the valves from the top to see if it clears any crap on the seat? It's certainly something to do with one or more of the inlet valves, but we need a bit more info on the noise to pin it down to being either small lumps of carbon or other muck on one or more of the valve seats, or, one or more of the inlet valves sticking in the guides due to carbon build-up on the valve stems. Is the 'popping' on a regular cycle and changing frequency in sync with any changes to engine rpm, or are the pops random and irregular ? |
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Post by Deleted on May 14, 2020 21:38:05 GMT
My engine has started making a popping sound through the air intake (no smoke). It's an isuzu 55. Its been a bit tappety, so the popping made me think intake valve. I've checked the clearances, and they were a bit out. I reset them, and the problem is not as bad as it was, but I still notice it a little on tick over. Can I spray wd40 onto the valves from the top to see if it clears any crap on the seat? It's certainly something to do with one or more of the inlet valves, but we need a bit more info on the noise to pin it down to being either small lumps of carbon or other muck on one or more of the valve seats, or, one or more of the inlet valves sticking in the guides due to carbon build-up on the valve stems. Is the 'popping' on a regular cycle and changing frequency in sync with any changes to engine rpm, or are the pops random and irregular ? Regular on tickover. When cruising it's not so noticeable, knock it out of gear, and it's ok for 5mins then gradually gets worse. It sounds almost as if it's not firing on all four. Revving it makes it not quite so noticeable, but I can still notice it slightly, like it's off beat, (if that makes any sense). |
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Post by TonyDunkley on May 15, 2020 6:22:42 GMT
It's certainly something to do with one or more of the inlet valves, but we need a bit more info on the noise to pin it down to being either small lumps of carbon or other muck on one or more of the valve seats, or, one or more of the inlet valves sticking in the guides due to carbon build-up on the valve stems. Is the 'popping' on a regular cycle and changing frequency in sync with any changes to engine rpm, or are the pops random and irregular ? Regular on tickover. When cruising it's not so noticeable, knock it out of gear, and it's ok for 5mins then gradually gets worse. It sounds almost as if it's not firing on all four. Revving it makes it not quite so noticeable, but I can still notice it slightly, like it's off beat, (if that makes any sense). Yes, it does make sense, . . and along with the regular frequency of the 'popping', it points to the cause being less likely to be a valve sticking in it's guide due to carbon build-up on the stem, and rather more likely to be some muck or carbon on a valve seat holding one inlet valve slightly open and off it's seat. There's a simple test you can do to check if this is the probable cause. With the air cleaner removed and the stop control set to 'stop' - if there's an 'energized to run' electric stop solenoid on the injection pump, disconnect and temporarily tape over the +ve feed wire to it at the pump end - then have someone crank the engine over on the key for you whilst you get your ear as close as possible to the inlet manifold and listen for a hissing sound as the affected cylinder goes through it's compression stroke. |
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Post by Deleted on May 15, 2020 7:37:26 GMT
Regular on tickover. When cruising it's not so noticeable, knock it out of gear, and it's ok for 5mins then gradually gets worse. It sounds almost as if it's not firing on all four. Revving it makes it not quite so noticeable, but I can still notice it slightly, like it's off beat, (if that makes any sense). Yes, it does make sense, . . and along with the regular frequency of the 'popping', it points to the cause being less likely to be a valve sticking in it's guide due to carbon build-up on the stem, and rather more likely to be some muck or carbon on a valve seat holding one inlet valve slightly open and off it's seat. There's a simple test you can do to check if this is the probable cause. With the air cleaner removed and the stop control set to 'stop' - if there's an 'energized to run' electric stop solenoid on the injection pump, disconnect and temporarily tape over the +ve feed wire to it at the pump end - then have someone crank the engine over on the key for you whilst you get your ear as close as possible to the inlet manifold and listen for a hissing sound as the affected cylinder goes through it's compression stroke. I've put a litre of redex in the tank, and dropped some into the inlet manifold. Set the tappets to the manufacturer advice and left it overnight. Started it this morning and seems a lot better. So I suspect you're right about carbon on the seat. I'll run it for a day or two and see if the snake oil sorts it. If not, strip down and repair I guess. Thanks Tony 👍 |
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Post by Deleted on May 15, 2020 7:45:53 GMT
a little bit of water can be quite effective.
(Edited to remove incorrect procedure).
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Post by Deleted on May 15, 2020 8:00:33 GMT
a little bit of water can be quite effective. (Edited to remove incorrect procedure). I'm a bit wary of that having taken the top off an engine and finding what looked like little ball bearings and pitted piston tops. The guy had used this trick. |
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Post by Deleted on May 15, 2020 8:06:57 GMT
Yes it is a bit dangerous I was surprised to see him pouring it in. If you get too much in you could hydraulic the thing which obviously be very bad.
I thought a squeeze spray arrangement would be better but perhaps not enough water gets in.
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Post by Deleted on May 15, 2020 8:11:43 GMT
Yes it is a bit dangerous I was surprised to see him pouring it in. If you get too much in you could hydraulic the thing which obviously be very bad. I thought a squeeze spray arrangement would be better but perhaps not enough water gets in. I'll see if I can get some normfest or similar and give it a dose of that. Bloody isuzu parts are hard to get, so I might be looking at a new engine. I don't want to go down that route until this bitching virus calamity sods off. |
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Post by Isambard Kingdom Brunel on May 15, 2020 10:03:16 GMT
No. It will do nothing. Decoke may be required with a valve reseating.
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Post by Deleted on May 15, 2020 11:25:31 GMT
@bedruthan is this issue related to high engine hours under low load? I'm interested because there is a lot of talk about diesels liking a bit of load. I wonder if you need to find some reasonably open water and give it a bit of a thrashing. I sometimes do this with my boat which has a Perkins P4 as that does tend to get a bit cokey if run slowly too much. Last time I did it I got quite a lot of solids and sparks out of the exhaust  |
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Post by Deleted on May 15, 2020 12:07:30 GMT
@bedruthan is this issue related to high engine hours under low load? I'm interested because there is a lot of talk about diesels liking a bit of load. I wonder if you need to find some reasonably open water and give it a bit of a thrashing. I sometimes do this with my boat which has a Perkins P4 as that does tend to get a bit cokey if run slowly too much. Last time I did it I got quite a lot of solids and sparks out of the exhaust Probably. I seldom go over 1000 revs, unless on the Thames. Even then I find 12-1500 revs ample. I did used to give it a thrash through perivale whenever I was that way, but I've stopped going into London. It's almost stopped now anyway. A good soak in redex seems to have sorted it. I'll maybe give it a thrash later if I get enough canal with no boats. Trouble is the bloody silt has fallen from the sides into the channel from no use I think, so it's a struggle to get any speed up. |
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Post by Deleted on May 15, 2020 14:10:26 GMT
Trouble is the bloody silt has fallen from the sides into the channel from no use I think, so it's a struggle to get any speed up. Yes but the engine would still be nicely loaded up Maybe wrong time of year as there are nests around. |
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Post by naughtyfox on May 15, 2020 16:36:48 GMT
The Curse of the Continuous Moorer. Valves all gummed up.
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