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After reading about the common issue with the 2zz and cam wiping, I decided to have a look at mine in the car that I just bought (and drove 800 miles home). The car is a 2005 elise with 55 kMi.
It appears that one of the intake cams is beginning to show wear: (I'll post a photo later, while I'm on my phone, Picasa won't give me a url for the forum). The finger test feels like 1/64th inch groove or so on the point of the cam.
I'm sorry man. I must be missing something? With casual inspection of your pictures I don't see thy type of wear.
Seems the acid test is if you can run your finger across the lobe and have it get caught on edges or ridges in middle. Maybe another with more discerning eye will see it and advise if anything than monitor. I would think with those miles if you had a bad cam you would know it by now?
I can see the wear you are describing on that one large lobe and can see that there is already a fair amount of metal worn off that lobe. If you run your fingernail across that lobe face I am sure you will feel the rough/uneven surface and be able to catch your fingernail on the unworn edges where the follower does not make contact with the lobe. The good news is that it doesn't look bad enough yet that the valve would be damaged, but I can guarantee the slipper pad on the follower is worn too. You could continue to drive the car, but this will only result in further wear to the cam and follower and most importantly damage to the valve they are actuating because of the hammering as the clearance opens up so I am afraid it is time to replace the cam and followers as soon as possible. This can be done with the rear clam still on the car and if you need directions on how to do this feel free to send me a PM.
Thanks for the responses; I'll be replacing this soon. Unfortunately, I was so fixated on feeling the groove in the cam that I didn't get a good look at the rocker.. I guess I'll have to open it up again before ordering parts.
To make matters worse, just today the car has developed a coolant leak in the front drivers side. 2 of the major elise problems in one weekend is a fair welcome to this toy after such a euphoric journey driving it home.
Well, the radiator replacement was a big endeavor, but it is done. The leaking that I previously observed was surely happening on a past drive, but after the 2 hour drive to get the car to a place where I could work on it, the coolant which had pooled in the grooves in the front fiberglass structure had dried up. The only evidence of the leak was the coolant residue left on the bottom of the radiator near the crimp. I decided to change it anyway.
The Wizard cooling Al radiator (1.5" core) only needed two holes added to the mounting tabs (on the DS where the AC condenser is attached at the top of the radiator) and slid in much easier than the old one came out, due to the cut tabs rather than slots in the mounting plate.
I opened up the cam cover again, and this time my old man measured the wear in the cam lobe: from the high point to the low on the one cam which was wearing measured 0.005". My father convinced me to not worry about this. I guess I'll periodically (at oil changes) measure the wear to see how it progresses.
As stated in my previous post, I had decided not to change the wearing intake camshaft or rockers and had instead chosen to monitor how the wear progresses over time.
During my first year of ownership, I never went above 6000 rpm. At the end of that year (3070 miles) I re-measured the cam wear and found that it had not progressed.
For my second year, I wanted more data so that when I finally found some progression of cam wear I could have an indication of what the cause was. From that point on, I decided to use the higher part of the rpm range once I waited for 10-20 mins after the coolant temp stabilized.
The leading theories for the cause of the cam wear include low cam hardness (I have not made a test for this), overly tight valve shim setting, and sub-optimal oil temperature. Since my car has two oil coolers, I am quite interested in probing the oil temperature idea.
I have made a poor attempt at measuring the clearance between the rocker and the bucket on the top of the valve stem- I cannot fit even a 0.006" shim between them (I checked on cams which were on the lowest pressure part of their rotation, but I could not easily slide the shim in). This suggests that the valve clearance was not set properly. I am still undeterred in my experiment.
I used metallic tape to secure a thermistor on the bottom of the oil pan and setup an Arduino to log the CAN packet which controls the gauge cluster as well as the thermistor reading to an SD card at a 1 Hz rate. I am aware that my oil temperature measure could be systematically low due to my probing location, but I think that the measure will be good enough. Now that the end of the second year driving season has passed, I took the logged data and prepared histograms.
I looked at the coolant temperature and oil temperature histograms as a function of time since engine start (I also have plots of engine speed and vehicle speed, but these are uninteresting). These plots show how quickly the operating temperatures normalize and what temperature variation there is within each fluid.
The coolant temperature and oil temperature seem to both rise quickly (within 15 minutes of engine start) to their steady state operating range. However, the oil temperature remains quite a bit lower than the coolant temperature. It also has a broader range of temperatures in its final distribution. Later operating times reveal an increased tail in the oil temperature distribution on the high temperature side, but the peak remains at the same point as in early operation time.
I have not measured the cam wear for this second driving season yet, but intend to do so in the spring. At that time, I will block off flow to one or more of the oil coolers and repeat the experiment.
Nice data presentation. One thing is for certain, your coolant and oil thermostats work.
The coolant thermostat is keeping your fully warm coolant temps at about 85*C, rarely going above 95*C, which tells me that you're not spending much if any time in hot weather, A/C on, stop-and-go traffic (lots of heat load with little air flow to the radiator). If you were you'd see more temps at least up into the cooling fan temp range (radiator cooling fans switch on at half speed at 94*C, full speed at 98*C).
Regarding the oil temp thermostat in the sandwich plate, your oil temp data confirm an opening temperature (opening flow to the oil coolers) of about 72*C, with little time spent with oil temps higher than 72. I expect you'd see higher oil temps with track time, but as it has been pointed out many times, the dual oil coolers are overkill for street-only driving. But I am a little surprised that the bulk of your oil temp data is significantly below the oil thermostat opening temperature. I can think of two possible explanations: your oil pan surface temperature underestimates the oil temperature at the sandwich plate by about 10-15*C, or else the sandwich plate thermostat starts to open at a lower temperature than the 72*C spec. Otherwise with no oil coolers (or oil thermostat always fully closed) I would expect the oil temps to roughly equal your coolant temps (with a time lag on oil temps).
...or else the sandwich plate thermostat starts to open at a lower temperature than the 72*C spec. Otherwise with no oil coolers (or oil thermostat always fully closed) I would expect the oil temps to roughly equal your coolant temps (with a time lag on oil temps).
My understanding is that the sandwich plate thermostat is a closing type. i.e. at low temperature some flow bypasses the oil coolers and some goes through the oil coolers- at high temperature the thermostat closes off the cooling loop bypass and forces all flow to go through the cooling loop. As I understand it, there is no operating mode where the cooling loop is removed from the oil flow path.
If the oil thermostat in the sandwich plate operated the same way as the coolant thermostat (i.e. keep oil in the engine block loop until it gets hot), then I would not expect to see such low oil temperatures.
Since I am not a thermostat engineer, I cannot easily conceive of an aftermarket or homebrew solution which would change this mechanism without adding an extra point of failure.
I really like the idea of the oil cooling loop, and would like the car to have a mechanism where the cooling capacity remains but the oil temperature is brought up to a reasonable level. The typical rectification routes involve the laminova cooler or a cooling loop removal. I may ultimately opt for the cooling loop removal, but I think that a more elegant solution must exist somewhere.
addendum: consistent with your observation of coolant temperatures I have not driven the car in super hot climate- Michigan is mild enough that I have not needed to turn on A/C, and as a weekend cruiser there is little stop and go traffic.
You drove a year without going over 6000 rpm? Wow lots of self restraint. I can't even make it to work without doing that. Nice informative post, thanks.
after the first year of data logging successfully, i assumed that the system was robust enough to go for a second year (third year of watching the cam wear).
so i drove with the oil coolers disconnected and didn't check the arduino log file for the entire duration of the driving season. i was very excited to see what the data would look like.
at the end of the season, i looked at the sd card, only to find a blank file -_- ..ugh, i failed to collect any data.
i guess I'll try again this year, but will actually look at the log periodically to see that it's collecting data
i haven't been able to perceive a change in the cam wear through measurement yet. the caveat here is that when i measure wear at the top of the cam lobe, i may miss wear that occurs along the egg shaped profile (in case the wear occurs just before the top of the rotation, for instance).
I'm still very disappointed in losing the data. at least i can pull the obd mode 0x22 performance data to see how much time I've spent in each rpm range this past year.
Nice data log....and when I got my Elise I immediately put a temp gauge in place that made me modify the system....I was rarely seeing 160 degree oil even on warm days. I just, upon suggestion from some here, put a different 185 thermostat sandwich plate in place...now I am normally 195-205.
I suspect (I've never looked at mine) that there are numerous Elise's with that same type/kind of wear motoring about without issue (street) as I think I see wear but the glare/reflection can deceive the eye.
If you do replace I'd go with a stock grind but harder (Rockwell measured) cam from someone like Monkeywrench...for some piece of mind.
This year my datalogging setup worked (although I did not drive as much as past years).
This log includes removal of oil cooling loop via the Toyota oil filter union.
It looks like I can reach higher oil temps without the cooling loop hooked up. However, the temperature of the oil never really stabilizes. I guess it shifts a lot with applied heat load; this is similar to other users' ( @cyow5 ) observation that oil temps rise fast when the engine is run hard if flow through the oil coolers are blocked. I can also see some heat displaced to the coolant system (as a high temperature tail).
At this point, it does not look like I drive hard enough to merit having the nice, higher-temp thermostat oil sandwich plate- I'm simply not adding enough heat to the oil. On the other hand, it would be nice to have a more stable oil temp (similar to the coolant temperature stability)- I can see how the Laminova would benefit both warmup of oil (to the water temp level) and temperature stability.
I can also see the time that it takes to reach peak temperatures increase compared to the log with the coolers active. I guess the heat delivery rate is probably similar, but the peak temperature is higher, so time to reach peak temps is a bit longer.
I have not looked at my camshaft wear yet this year to see how it's progressing.
Points worth noting:
1. automotive engines are not designed around the assumption that oil temperature will be constant when the engine is operating. Neither are engine oils. A minimum desirable engine oil temperature is about 85 C to decrease water and fuel dilution of the oil. Continuous operating temperatures as high as 110 C are fine, and brief excursions to 120 C are beneficial if you want to get rid of diluents. Most street driven cars have trouble maintaining oil temps above 85 C in winter. An oil to water cooler (as fitted to EU spec 111Rs) can help with this.
2. All mass produced camshafts I know of are made of a mild iron with a carburized case hardening applied after grinding the lobe profile. This is because mild iron is easy to grind and also because it copes with shock loads (like camshafts experience as they bounce valves open and closed). As others have noted, once the case hardening is worn through, you have mild iron rubbing against fairly hard steel followers and wear accelerates.
What's probably saving you on the high speed cams of a 2ZZ-GE is that the big cams aren't engaged very often, particularly on a mildly driven street car. I'm curious to see what your wear looks like this year.
I have a parts 5S-FE I can steal the oil-water sandwich cooler from. That'll be going on my Elise this winter.
@Obeisance - I realize you’ve been running a damaged camshaft for some time, but no one has mentioned an important fact about the materials involved. The camshaft is surface-hardened, so once you bust through the hard layer, the metal-to-metal interface will wear rapidly and dump metal particles into your engine oiling system. If you’ve detected damage to the camshaft - especially the nose which sees very high pressures - you are most likely dumping metal particles into your engine oil. It’s an understatement to say that’s not recommended.
i also don't really know anything about this camshaft's hardening treatment- if it's a bake-in-CO2-carbonization or a coating, then it would certainly be a thin layer. But i thought that some steels that don't need large plasticity are hardened via a heat-and-quench to martensite process (whixh i expect to be homogeneous).
in any case, based on the wear pattern (smeared metal and missing material), I'm inclined to believe that the hardening is only surface deep.
on the other hand, what are the chances that a cam that's worn through the hard layer will begin to work harden in the softer layer and recover some resilience?
early in this experiment, i was close to buying a $200 Vickers indenter tip from ebay so that i could check hardness at various worn and unworn parts of the cam in situ (i figured i could get by with a usb microscope since the Vickers measurement is simple). maybe i should revisit this idea..
I'm still not inclined to rush into changing the camshaft, but maybe i should check other parameters like cylinder compression more often.
Cylinder compression won't tell you anything about the big lobe's health. I will hint though that removing the valve cover becomes a little over a 5 minute job with an electric drill/screwdriver...
Here is a random article about camshaft hardening: CPG Nation / Camshaft Heat Treatment. It echoes what I’ve read elsewhere . .. most camshafts have some variable depth of surface hardening with a soft core. The latter keeps thing flexible enough to avoid fracture, while the hard surface provides wear resistance. For an analog, this is exactly how a twist drill is engineered.
Some hardening treatments have a fairly substantial depth while others are very thin. Based on the number of cam wiping reports, I’d guess the Toyota cam surface hardening method produced a very thin layer.
These layers are actually visible to the naked eye (oftentimes) so we just need someone with a band saw and an old cam to slice one down the middle of the big lobe. You can also then run a hardness test on both the surface and the interior to figure out if it is below average or not.
It looks like I may be flying out to look at a car for sale. If I decide to check for cam wiping, it looks like I will need a 10mm socket and ratchet, pliers and flat blade screwdriver for the hoses? Is there anything else? I'm mechanical but haven't done it before. Is that something you guys would reasonable think could be done during an inspection to buy and how long would you expect it to take?
Thank you. I will watch this over lunch. Regarding the PPI, I have thought about that and wanted to do it. However this car is 4-5 hours away from a lotus shop.
I had same issue and found a euro indie shop that was willing to do it with canned app they had. You'll want to check bushings, brakes, whether it's had it's recalls done, check if oem or aftermarket radiator among all the other items listed in the buying hints in the Elise section. It can make or break price if negotiating.
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