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I run an outboard repair service in the UK, and a customer brought in a 2007 DF15 which he said was not running correctly. The oil was heavily emulsified. Lower cylinder compression test wasn't good and I noticed water droplets on the lower plug so tore the engine apart. What I found was severe corrosion in the lower combustion chamber, rusted valves, springs etc, and seized lower piston rings. Sea water must have been getting in there for a long time. Bearing surfaces / bores etc are still in spec so $350 of new parts ordered and rebuild is in process. When I measured the flatness of the cylinder block head mating surface I discovered a manufacturing burr / raised edge where the head face adjoins the oil pan mating face. So I guess in the factory they had machined the cylinder block head mating surface first, and then machined the oil pan mating face last leaving a machining burr on the cylinder block mating head mating surface. This burr prevents the cylinder head sitting true to the cylinder block head mating surface, and I have measured a gap of .002" which uses up all of the flatness spec for this mating face. So I am now thinking no wonder the head gasket failed because it was never seating correctly in the first place because of this burr. Has anyone else come across this problem??
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Jon
first, I noticed you are new here on the forum and secondly, being in the engine repair business, your comments and observations are going to be very helpful to a lot of folks that post questions here..
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To your post and question, you may not find comments better that what you have observed.. my only, non technical, question would be.. at only .002 off level, would not the gasket compress enough to be able to compensate for that small of a distortion?
I would think from the pictures you posted on the other thread, and you should also post them here as well, this engine looks to have swallowed a bunch of salt water, besides of not being cared for, and maybe not ever even had an oil change, from the sounds of it...
I have been here for several years now and have not seen a question like the one you have asked.. however, this forum does have a search page. To search, you have to go to the "advanced" search page to use it..
Art.. -
Hi Art, many thanks for your response. It seems that the burr alone I mention, lifts the cylinder head up by about .002" around that area. As the spec says a maximum of .002" gap is allowed, that means that the actual surface of the cylinder head needs to be completely flat with no variation at all. I have measured it and it actually has variation of around .002" so my total variation is .002" + .002" = .004", so it is well over spec. I don't think the head gasket will cope with that level of variation so I am going to lap it on my granite surface plate. Your are right that the engine hasn't been looked after, oil was badly emulsified, original oil filter etc. So I guess neglect and the manufacturing flaw (including poor surface finish / machining marks) has led to the engine failing in the way it has, which is a shame because there doesn't seem to be many hours on it. I will do that search on the site as you mention and have attached the photo. Many thanks and best regards, JonComment
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