cam wiping early catch: what to do? - LotusTalk - The Lotus Cars Community
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post #1 of 34 (permalink) Old 04-25-2015, 08:46 AM Thread Starter
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cam wiping early catch: what to do?

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.



https://docs.google.com/file/d/0ByGx...p=docslist_api

https://docs.google.com/file/d/0ByGx...p=docslist_api

My question is this: with this amount of wear, what should I do? Replace the cam? Change the shim/cup on the top of the valve? Carry on and ignore it?

Can I keep driving (just don't use the second cam)? Is this a death sentence?

Edit: compression test have all cylinders between 212-220 psi.

Last edited by Obeisance; 04-26-2015 at 06:27 AM.
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post #2 of 34 (permalink) Old 04-25-2015, 10:30 AM
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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?

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post #3 of 34 (permalink) Old 04-25-2015, 11:28 AM
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If you can feel a ridge I would replace the intake cam. Once they start to go they usually go quickly.
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post #4 of 34 (permalink) Old 04-25-2015, 12:02 PM
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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.
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post #5 of 34 (permalink) Old 04-25-2015, 02:24 PM Thread Starter
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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.
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post #6 of 34 (permalink) Old 04-25-2015, 02:28 PM
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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.
Dang, that's some sour luck. On the bright side, after you get these two issues resolved you'll have smooth sailing for a long time.

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post #7 of 34 (permalink) Old 04-26-2015, 05:36 AM
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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.

Keep your head up! The radiator swap isn't terrible but it costs money you'd rather not have to spend. It is a good move though as you will be fixing one of the main items that threatens to leave you stranded. The other being that cam. You'll also find tons of "removing my clam this weekend; what else can I work on?" threads that show how to do things like take care of the HVAC resistor pack, HID install, stainless brake lines, etc.

You'll then begin the slippery, steep slope of "well, I might as well buy shocks and springs, too, since the clam is off. Oooooh, brakes...."

And then you'll officially be a part of the club


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post #8 of 34 (permalink) Old 04-26-2015, 10:45 AM
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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.
not really " major problems " on the Lotus scale.

I have a little right up on cam replacement here.

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post #9 of 34 (permalink) Old 04-26-2015, 11:32 AM Thread Starter
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I have a little right up on cam replacement here.

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That writeup is just what I needed to see; thanks for that!
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post #10 of 34 (permalink) Old 04-26-2015, 04:11 PM
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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.
You get a new set of rockers with the new cam (even if your old rockers were OK, you cant use a new cam with used rockers or you will quickly ruin your new cam) so there is no need to open the motor back up.
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post #11 of 34 (permalink) Old 04-26-2015, 04:18 PM Thread Starter
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You get a new set of rockers with the new cam (even if your old rockers were OK, you cant use a new cam with used rockers or you will quickly ruin your new cam) so there is no need to open the motor back up.
After reading a bit more about this, I arrived at the same conclusion. Thanks for reinforcing the idea. So far the best price I've found for the stock replacement kit is via an online Toyota parts store at about $205 for the cam and rocker set. Of anyone knows a better source, I'm open to suggestions (same with the radiator.. So far I think I'm gonna go for the cheap wizard option).
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post #12 of 34 (permalink) Old 05-31-2015, 06:06 AM Thread Starter
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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.
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post #13 of 34 (permalink) Old 11-26-2016, 04:16 AM Thread Starter
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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.
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Last edited by Obeisance; 11-26-2016 at 09:17 AM.
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post #14 of 34 (permalink) Old 11-26-2016, 07:13 AM
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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).

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post #15 of 34 (permalink) Old 11-26-2016, 07:44 AM Thread Starter
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...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.
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post #16 of 34 (permalink) Old 11-26-2016, 07:54 AM
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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.
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post #17 of 34 (permalink) Old 02-20-2018, 11:55 AM
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How'd this ever come along?

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post #18 of 34 (permalink) Old 02-20-2018, 12:11 PM Thread Starter
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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
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post #19 of 34 (permalink) Old 02-20-2018, 01:23 PM
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You didn't have supporting data, but did your cam wear any further in year 2, when assumably you started going to redline?

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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

"Give a man a match, and he'll be warm for a minute, but set him on fire, and he'll be warm for the rest of his life."
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post #20 of 34 (permalink) Old 02-20-2018, 01:48 PM Thread Starter
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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.
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