How smooth do cam lobes need to be?

[ABN_CBT_ENGR]

If I return the whole thing for a cash refund there’s a 25% restocking fee. Besides, he said I voided the warranty by taking the valve cover off so he can’t take it back. What a bunch of BS! Taking the valve cover off to check and adjust valve lash is literally part of Honda’s maintenance schedule! So does taking the oil filter off void the warranty too?

All he related to you is unenforceable and would lose in any litigation (assuming your claim and account is valid) but the cost and time makes the action prohibitive ( that's where they get you)

 

[SatinSilver]

When will the shop have the cleaned up cam ready for pick up? Wouldn’t mind seeing a picture of it.

 

[ABN_CBT_ENGR]

That's a good idea, I am going to the engine shop to talk to him in a little while. He seemed to be insisting that rust is normal since it has been sitting in a humid warehouse for a while and if I just run it the cams will clean themselves up. I'm not buying that though,

His claim is simply incorrect and patently false but it seems you don't have a full understanding of what you are looking at so making your case is very weak indeed.

The pitting is not "rust" nor did it come from or is a result of "rust" or any other chemical reaction. That's a red herring. This is not "surface rust". This is destructive pitting.

The pitting follows the lobe path- it is a result of a mechanical fatiguing action ( specifics unknown)

The "rust" is the normal sequence of events when metals are altered and worked beyond certain hardness depths to softer base metal.

The "rust' isn't the problem- the reason the rust is there in the first place is the problem.

 

[Avery4]

His claim is simply incorrect and patently false but it seems you don't have a full understanding of what you are looking at so making your case is very weak indeed.

The pitting is not "rust" nor did it come from or is a result of "rust" or any other chemical reaction. That's a red herring. This is not "surface rust". This is destructive pitting.

The pitting follows the lobe path- it is a result of a mechanical fatiguing action ( specifics unknown)

The "rust" is the normal sequence of events when metals are altered and worked beyond certain hardness depths to softer base metal.

The "rust' isn't the problem- the reason the rust is there in the first place is the problem.

I have a pretty good understanding of what I am looking at, I have built a few engines over the years including the one that's in my car now. However, I am by no means a professional engine builder or a metallurgist and I don't have the experience to say for sure whether that pitting would be a problem, although I would assume it would be.

The pitting does in fact seem to be a result of the rust since all the other cam lobes look great and the pitting is directly under where the rust was. Again, I'm no expert though

 

[Avery4]

When will the shop have the cleaned up cam ready for pick up? Wouldn’t mind seeing a picture of it.

I'm going to go drop those cams off this afternoon for "cleaning", he didn't say for sure when I will be getting them back. I will definitely post an update with pictures when I get the cams back and/or get a resolution.

 

[wpod]

What is wrong with the rest of the JDM engine. This doesn't instill confidence

 

[ABN_CBT_ENGR]

I have a pretty good understanding of what I am looking at

The pitting does in fact seem to be a result of the rust since all the other cam lobes look great and the pitting is directly under where the rust was. Again, I'm no expert though

Fair enough, but you might profit by listening further to those with a background in metallurgy.

Look at the physical evidence in front of you with no preconceptions and don't jump to anecdotal conclusions like "its here but not there" as if that means anything because in cases like this, it doesn't.

Its not that the pitting is "under the rust"- the "rust" is the normal top coating of the pitting.

In this respect, the pitting on a cam lobe is no different than the pitting on a gear tooth and the clue that defines it is the contact pattern of the pitting. ( rust is generally random in consistency and starts with an exposed surface with oxidizers)

If you don't think this is a problem, "clean it" ( defined as remove mass/dimension and get closer to the softer core as is the result of normal carburization treatments and change surface finish) and give it a little time running against the hardened surface of the rider ( whatever it is)- this particular "problem' is going to come back like Matt Hooper described it in Jaws.

 

[Trav]

That's a good idea, I am going to the engine shop to talk to him in a little while. He seemed to be insisting that rust is normal since it has been sitting in a humid warehouse for a while and if I just run it the cams will clean themselves up. I'm not buying that though, I have a Honda D17A2 motor that has been sitting in my humid garage for nearly 2 years and the cam doesn't have the slightest bit of rust on it.
I am going to ask him to either find me a usable set of cams or give me $150 back so I can buy a usable set of cams, $150 is about what they are selling for online. I think that is very reasonable considering how those cams look.

I Recall reading that export parts coming into the US must be cleaned to remove any possible traces of dirt.

 

[andyd]

You have the head off. Flip the engine over, pull the pan, check out a bearing or 2. clean stuff up , replace front and rear seals. Replace cams,even if you have to pay for them. I would have pulled the valve cover before buying a used engine, just cuz. Caveat emptor. I'd want as strong an engine as I could make it. Please post more on your engine swap progress

 

[mattd]

Those are definitely junk. Don’t use them.

 

[ZeeOSix]

Avery4 - is every single cam lobe showing that same pitting pattern and amount of pitting? Or are some of the lobes located away from the area where water might have gotten into the valve train look good with zero pitting?

If the pitting is destructive wear, and are factory cams, then I'd think the cause would be from a lack of proper lubrication. What to the follower's contact area look like? If they are factory cams, then it would be hard to imagine they had bad metallurgy from the factory, but anything is possible. If those are cheap aftermarket cams, then maybe it's pitting from bad metallurgy. I had a Honda V4 motorcycle that showed destructive wear on the cam lobes, and it was from bad metallurgy and lack of lubrication to the top end. Honda replaced them under warranty and had a fix to get more oil to the cams.

 

[PimTac]

They have had a number of major floods in Japan. A unscrupulous person might have been selling those engines/vehicles to a developing country and they got bought and rerouted to here. It happens a lot more than you might think.

 

[Avery4]

Thank you for your help everyone, I really appreciate it! I just dropped those cams off and he told me that he will have them cleaned up by a machine shop and they will be done by Monday. Not sure if that is possible especially as bad as the rust on the intake cam is, we will see how they look, I will post pictures as soon as I get them back. My concern is as bad as the rust on the intake cam is, I imagine that the machine shop will need to remove quite a bit of material to get it smooth again and I am concerned that the engine's performance may be adversely affected by the cam's lift being reduced. Is this a valid concern? I never took a cam to a machine shop to have rust removed, so I;m not sure. Thanks in advance! Here are pictures of how the cams looked when I took the valve cover off.

 

[ABN_CBT_ENGR]

Based on a visual in situ review of your pictures ( with a significant degree of error due to inability to examine properly)

You appear to have black and brown rust ( almost magnetite looking) which usually comes from an acidic low oxygen reaction with metal.

If that's accurate then it indicates running with inadequate lubrication ( anywhere from wrong film strength, depleted additives, excess heat- impossible to diagnose visually) generating excessive localized heat. ( that's more based on the observation that the "oxidation" is localized in wear paths specifically but an even presence over most of the compartment otherwise)

If that's correct then the "pitting'( corrosion initiated) is more likely "spalling" from fatigue. ( based on the "absence" of the "pitting" everywhere else).

If that's correct then they are non serviceable ( they may run the engine but will wear faster now and probably cause more damage)

I don't know what they mean by cleaning but if they change finish, surface hardening, geometry or dimension- they are likely to make a bad situation worse.

 

[supton]

Cam grinders can reduce the base circle of the cam and keep (or even increase) cam lift. Requires the followers (buckets, whatever it may be) to take up the slack. I would assume a cam grinder can do whatever surface hardening required--but I'm also not sure that they can achieve whatever longevity that an OEM can hit.

 

[Avery4]

Based on a visual in situ review of your pictures ( with a significant degree of error due to inability to examine properly)

You appear to have black and brown rust ( almost magnetite looking) which usually comes from an acidic low oxygen reaction with metal.

If that's accurate then it indicates running with inadequate lubrication ( anywhere from wrong film strength, depleted additives, excess heat- impossible to diagnose visually) generating excessive localized heat. ( that's more based on the observation that the "oxidation" is localized in wear paths specifically but an even presence over most of the compartment otherwise)

If that's correct then the "pitting'( corrosion initiated) is more likely "spalling" from fatigue. ( based on the "absence" of the "pitting" everywhere else).

If that's correct then they are non serviceable ( they may run the engine but will wear faster now and probably cause more damage)

I don't know what they mean by cleaning but if they change finish, surface hardening, geometry or dimension- they are likely to make a bad situation worse.

Thank you for your help! I have no way to know the maintenance history of this engine, but it does look very clean inside and the cam lobes that weren't rusted appeared to have no visible wear. I think if the engine ran with inadequate lubrication for whatever reason there would be damage to all the cam lobes and likely the cam journals also, at least that has been my experience.

I was wondering if maybe this engine ran hot because a lot of the plastic parts seemed quite brittle. For example, each of the 4 fuel injector connectors under the intake manifold cover broke when I squeezed the tabs to unplug them. But there is no leakage into the coolant that I could detect with a leakdown test, no mixing of coolant and oil, and the cylinder walls look good, so I have no reason to think the engine was damaged if it did run hot.

 

[Avery4]

Cam grinders can reduce the base circle of the cam and keep (or even increase) cam lift. Requires the followers (buckets, whatever it may be) to take up the slack. I would assume a cam grinder can do whatever surface hardening required--but I'm also not sure that they can achieve whatever longevity that an OEM can hit.

That makes sense, but I don't know that whatever machine shop he is taking these cams to would care enough to make sure that the lift remains unchanged. As crappy as this guy has been to deal with, I presume he is going to tell the machine shop to just make the cams look alright to shut his customer up for as cheap as possible.

 

[ABN_CBT_ENGR]

Well, to avoid semantics

"Inadequate lubrication" is a high level failure mode that needs to be defined by the mechanisms in context with tribology- it doesn't just default to not enough oil or the entire oil was bad per se.( which theoretically would be uniform throughout the machine)

Given the picture, your engine seems to have a more localized problem ( which could have a hundred contributing failure mechanism) with the lubrication inadequacy being a contributing factor.

But I tend to stick with the facts in evidence ( in this case just examining a picture), this appears to be "black rust" with spalling in a wear path.

If that's just a picture artifact then all bets are off but if it is, that's very telling and the basis of my "virtual assessment" (LOL)

 

[dnastrau]

Avery4, do you know what machine shop this guy uses? I would be surprised if a good machine shop would try to "clean" the rust off of those cams and then stand behind the work.

For all we know, this guy will dump the cams in a vat of EvapoRust or vinegar over the weekend and hope for the best.

Good luck - I hope this works out in your favor.

Andrew S.

 

[Trav]

Cam grinders can reduce the base circle of the cam and keep (or even increase) cam lift. Requires the followers (buckets, whatever it may be) to take up the slack. I would assume a cam grinder can do whatever surface hardening required--but I'm also not sure that they can achieve whatever longevity that an OEM can hit.

True but not every jamoke can do this sort of work, it is very specialized. The only place these cams would going if it were mine is the bin.