Honda wants $1K for a new bare head. The machine shop thinks the scoring might be passable if they "lightly recondition" surfaces but removing the broken spark plug remains the primary concern at this point.
Honda J35 V6 (J35Z4) Sludge and Cam Scoring
- Thread starter The Critic
- Start date
yeesh... is that complete with valves and springs or bare?
From the diagram, it looks like a bare head.
I'd clean it up a little with some Scotchbrite then Bore Gauge it against Honda specs.
I'm going to agree. I've known of fleet vehicles using extended OCI's and quality synthetic oil, no such deposits were visible.
It would come with valves and springs. I feel like replacing the one head might be the best option. Then change to 5000 mile oil change intervals.
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VCM engines are the equivalent modern day sludge monsters, but this example is definitely an unusual case.
If it was my car i would also go with a used head.
However i guess this is more common so it is hard to tell if the used had will also have this problem.
This EDM peugeot 1.4 16v did aslo have severe cam scoring on cam bearing ledge. (common problem) This vehicle was also only used for very short distances and was verry dirty.
This was noticed because it had a leaking headgasket so the head had to come off. However it ran fine before dismanteling.
However i guess this is more common so it is hard to tell if the used had will also have this problem.
This EDM peugeot 1.4 16v did aslo have severe cam scoring on cam bearing ledge. (common problem) This vehicle was also only used for very short distances and was verry dirty.
This was noticed because it had a leaking headgasket so the head had to come off. However it ran fine before dismanteling.
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Final Update:
- Head came back from the machine shop after 2.5 weeks. They were unable to remove the stuck plug with an extractor and had to drill it out. The machine shop did not have a Timesert kit for the newer M12x1.25 plugs so I had to acquire one at my expense ($250). The machine shop cleaned the sludge, installed new valve stem seals, did something to journals (did not ask), resurfaced the head, installed the new cam and installed a Timesert in #4. And FYI, a 24mm insert is almost a perfect fit for these heads, maybe a hair long.
- Rear cylinder head was normal. No sludge, just moderate varnish.
- Valve adjustment was performed on the rear head as well. Intakes were loose, exhaust valves were on the tighter end of spec but probably still passable. I set the valve clearance on the loose end of spec (.009" for intakes and .013" for exhausts).
- Found #1 plug to be fouled which is typical for the older VCM engines. Installed 6 new NGK plugs and torqued them to 16 ft lbs with a little bit of anti-seize (per the FSM). Also flashed the PCM with the latest calibration which contains revised VCM switching logic.
- Timing marks were 1/2 tooth off upon reassembly, probably due to the head resurface.
- Engine is running fine after the repair. At idle it is dead quiet, no more knocking sounds. No misfires, fuel trims are well within spec. During acceleration there is some light clatter, but this is probably a combination of the valve clearance being on the loose end of spec and other worn parts.
- Head came back from the machine shop after 2.5 weeks. They were unable to remove the stuck plug with an extractor and had to drill it out. The machine shop did not have a Timesert kit for the newer M12x1.25 plugs so I had to acquire one at my expense ($250). The machine shop cleaned the sludge, installed new valve stem seals, did something to journals (did not ask), resurfaced the head, installed the new cam and installed a Timesert in #4. And FYI, a 24mm insert is almost a perfect fit for these heads, maybe a hair long.
- Rear cylinder head was normal. No sludge, just moderate varnish.
- Valve adjustment was performed on the rear head as well. Intakes were loose, exhaust valves were on the tighter end of spec but probably still passable. I set the valve clearance on the loose end of spec (.009" for intakes and .013" for exhausts).
- Found #1 plug to be fouled which is typical for the older VCM engines. Installed 6 new NGK plugs and torqued them to 16 ft lbs with a little bit of anti-seize (per the FSM). Also flashed the PCM with the latest calibration which contains revised VCM switching logic.
- Timing marks were 1/2 tooth off upon reassembly, probably due to the head resurface.
- Engine is running fine after the repair. At idle it is dead quiet, no more knocking sounds. No misfires, fuel trims are well within spec. During acceleration there is some light clatter, but this is probably a combination of the valve clearance being on the loose end of spec and other worn parts.
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Personally, I recommend you telling the customer to probably drop back to 1/2-3/5s OC interval with probably a cover off visual inspection annually.
Based solely on the pictures you posted and your account ( and without testing the sludge or cam), I believe I can tell you what clearly didn't happen so when you remove that- whats left is what needs to be looked for.
It was in no way a defective cam (in terms of metallurgy or heat treat) and anyone who does metallurgy and treatment can clearly see that based on the pictures. Anyone who doesn't have a working knowledge of that science shouldn't be making a technical evaluation in the first place.
First, when metallurgy or heat treat is screwed up- the entire batch suffers the same fate and the 'whatever" is uniform. This cam shows no evidence of any torsional stress, ratchet lines, unusual wear patterns, discoloration or anything else. It does however show work hardening induced fatigue ( along a contact path) The case of bad cam loses all strength when this is isolated to select lobes- you cant "half treat" anything in a batch furnace.
That eliminated the cam as being a cause- it is the victim.
That work hardening- that comes from a combination of 3 inputs. The hardness, the load and the lubrication.
I cant go further because cant see any mating surfaces and specific loading is unknown but the varnishing leads me to believe the oil is being broken down ( which is not a failure of the oil if the change history and type is accurate so I take that at face value that it is)
All that leads me to believe there is one or more mechanical issues in this specific engine ( which may be corrected with this repair) that together contributed to this failure.
That's why I recommend scaling back the OC and an inspection to catch patterns in an early stage next time (or show there wont be a next time because its fixed)
Based solely on the pictures you posted and your account ( and without testing the sludge or cam), I believe I can tell you what clearly didn't happen so when you remove that- whats left is what needs to be looked for.
It was in no way a defective cam (in terms of metallurgy or heat treat) and anyone who does metallurgy and treatment can clearly see that based on the pictures. Anyone who doesn't have a working knowledge of that science shouldn't be making a technical evaluation in the first place.
First, when metallurgy or heat treat is screwed up- the entire batch suffers the same fate and the 'whatever" is uniform. This cam shows no evidence of any torsional stress, ratchet lines, unusual wear patterns, discoloration or anything else. It does however show work hardening induced fatigue ( along a contact path) The case of bad cam loses all strength when this is isolated to select lobes- you cant "half treat" anything in a batch furnace.
That eliminated the cam as being a cause- it is the victim.
That work hardening- that comes from a combination of 3 inputs. The hardness, the load and the lubrication.
I cant go further because cant see any mating surfaces and specific loading is unknown but the varnishing leads me to believe the oil is being broken down ( which is not a failure of the oil if the change history and type is accurate so I take that at face value that it is)
All that leads me to believe there is one or more mechanical issues in this specific engine ( which may be corrected with this repair) that together contributed to this failure.
That's why I recommend scaling back the OC and an inspection to catch patterns in an early stage next time (or show there wont be a next time because its fixed)
I love these guessing games!
I'll take door number 3.
I'll take door number 3.
Every analysis is a "guess" or didn't you know?
After that, the quality of that "guess" rests in the analysis particulars and the qualification of the one(s) doing the analyzing.
So, what "guess' leads you to door #3?
I could be wrong but I was under the impression these camshafts are induction hardened.
Without seeing the actual heat treat plan and based on current practices I am familiar with, I would say that's almost a certainty. ( but could be flame)
That's a big part of what I was pointing out regarding uniform treatment- its almost impossible to have an un-uniform magnetic field
True, but it is in line process (as opposed to say, an old school batch vacuum furnace or as you wrote "batch furnace") - so while I doubt there would be mass quantities of cams with relatively softer areas, the problem could be more isolated to single cams, or a few lobes and/or journals if the coils or power supply are having issues. All this is speculation of course. Never been in a Honda auto engine factory.
It can be any number including inline batch depending on the contract, machine used and whatever the graph shows for the requirement. That's the part we don't know. ( for the purposes of this, its not critical)
Not possible in any modern set up. This is still a highly controlled environment with sensors everywhere and anything like that would alarm to wake the dead.
Even if it were to happen, nothing shown on this ( or 99.99% of the other claimed "improperly treated" stuff I have had to analyze over the years) indicates the presence of a treatment related anomaly.
If one thinks about it, typical induction processes add a top layer of skin ( skin effect) residual compressive stress that can act as a crack arrestor and further strengthen it. Looking at different wear rates on the other surfaces indicated this was not only present but worked to the point it was mechanically worn through.
Like I said, there is nothing shown that is determinative of an issue with metallurgy, atmosphere cycle, dwell or quench.
Available evidence does however point to a mechanical issue. Not dismissing the fact that an improperly treated cam wouldn't have survived the life it did in the first place.
Have to look at the available evidence from all angles.
Update:
Car still runs fine. It has been 20K miles since this work was done.
Car still runs fine. It has been 20K miles since this work was done.
The information is the reason people are doubting that is the primary issue. One side of the engine shows no sign of the oil change being overextended and the other appears to have suffered partial oil starvation. It looks a lot like an engine that had inadequate venting and suffered from moisture induced sludge but on one head only (That's an observation on appearance not an opinion on cause).
I THINK you meant to write "believer". The sarcastic comment does not help your lack of clarity or your, well, misinformation.
Simply: An extended OCI does NOT mean the same as lack of maintenance. It's a pretty basic concept.
In this case, we are trying to learn, and yes, with some speculation, the actual root cause.
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