Camshaft cover defect causing rocker-arm breakage (P1302)?

[insane]

Badnis on exiges.com—in a thread documenting rocker-arm breakage and P1302 codes—suggested that the high-lift intake cams may be getting improper distribution of motor oil from the overhead oil feeds in the camshaft cover. He backed that up with a photo of a test conducted in his shop where fluid was circulated through the camshaft cover system, which appeared to show less-than-desirable flows.

Well, I thought this was plausible, and—along with my buddy Nick (ZTEC)—felt it would be worth trying to repeat Badnis’ experiment. We first tried to avoid any mess by trying a quick CSI-type setup (sorry, no lasers!) to see if there might be anything to this. The first shot is Badnis’, from exiges.com, the next two are our dry tests. The results warranted further investigation.

[insane]

The following shots are the wet experiments. It’s clear that the direction of oil spray for intake cam lobe #3 is directed differently from the other seven oil streams.

Careful measuring further shows that—since the oil distribution structure in the camshaft cover is narrower-than, and centered-over the intake/exhaust cam pair—the spray streams must be directed slightly laterally to be effective. It is obvious (at least, in my case) that Intake #3 is directed inward.

In order to adequately coat the leading and back side of the spinning cam lobe, the oil stream should be directed toward the centerline of the spinning camshaft—over the High-lift cam lobe. It’s likely designed this way since the rocker-arm pad (at the top of the tappet) is not a low-friction roller, which I’m sure generates a lot of heat.

Nick does a great (and creative) job here of setting up the ‘lab’.

[insane]

In these shots, Nick turns the cover over to observe what might be happening in the operational orientation.

[insane]

...if those of you who have repaired (or will be repairing) one of these, have you replaced the camshaft cover? Just consider that it may be the cause of the problem.

Anybody who has had this repair done under Lotus warranty.... did Lotus replace the camshaft cover?

[Rugbyduck]

Pretty damn good illustration! The trick is how to fix it!

[insane]

You can bet that when I fix mine, there's going to be a new camshaft cover.

Here's my damage at this link.

[akandok]

would it be possible just to re-drill the hole?

[Dragon]

good find and good demo, would be nice to see a few others done in this way to find out if they are all bad, or just a certin few. Would also like to see a Celica 2zz one done as well to see if toyota tried to hook lotus up...

[ZAMMY1]

that's an impressive find!
you guys are good!
sam

[AlanS]

Great work! I posed the theory of a lubrication problem in the cam cover to my dealer after my failure and never heard any followup from the dealer or Lotus. At the time I didn't know that the problem was endemic to the #3 cylinder and speculated that there culd be an obstruction in one f the passages. Great to see someone document this!

[ZTEC]

Visually you could see the #3 "sprinkler" was off on the intake side if you were looking down the line from the side. It is obvious this was not intended during manufacturing and is a defect in at least Michaels valve cover - It was interesting to see how the fluid reacted under different pressures as well - More pressure and the stream staightened up pointing the fluid further inboard away from the cam.
At the very least a visual inspection of your cam lobes are in order and if you see any wear on the lobes that is not in line with your mileage or obviously different than the others, Take a good look at your valve cover and the lubrication system.

Now comes the speculation into how many made it past Quality Control into our cars?

Thanks Joshua (lotushark) from Fourniers for the phone advice

[insane]

Originally Posted by akandok

would it be possible just to re-drill the hole?

That'd be difficult; size, direction, position.... plug original hole?

Originally Posted by Dragon

good find and good demo, would be nice to see a few others done in this way to find out if they are all bad, or just a certin few. Would also like to see a Celica 2zz one done as well to see if toyota tried to hook lotus up...

That would be excellent.... if others could test to prove or disprove this hypothesis.

Originally Posted by AlanS

Great work! I posed the theory of a lubrication problem in the cam cover to my dealer after my failure and never heard any followup from the dealer or Lotus. At the time I didn't know that the problem was endemic to the #3 cylinder and speculated that there culd be an obstruction in one f the passages. Great to see someone document this!

The dealer? (sorry, there are probably some who would actually go through the trouble)

[Devious]

You can replace the oil shower tubingwith similar size tubing, but it is possible to braze or weld up the holes and then add correctly aim new ones at selected points along the cams to lube and cool better than stock. I have done this recently as part of the blueprinting to improve the details not possible in the manufacturing process.

Another point to consider is the viscosity of the fluid (hot oil) you are spraying versus the size/shape oriface in the tubing. Just as with the oil squirters in the block, the size and shape will determine the spray pattern and volume. The holes earlier in the circuit may need to be smaller than the ones that are fed oil at a slightly lower pressure due to being located later in the circuit.

If you alter the tip shape of the drill bits you are using to re-drill the holes, you can produce a small cone in the hole opening that produces a cone-shaped spray pattern instead of a simple stream. This will allow the oil to cover a slightly wider area of the cams and rockers. I used smaller holes than stock, but more of them. Then I drilled the openings using slightly larger bits with varying narrow-angle tapers cut into the ends to produce small cone-shaped jets.

Oil drain back in the head and block can be improved as well. The blocks and heads of the 2zz-ge engines I have, all needed the considerable internal casting flash removed, and a good coating of Glyptol or other oil shedding coating.

Just my .02, but I hope it helps.

[GTsRasta]

VERY NICE DETECTIVE WORK!!!

Was it like that from factory, or did it deviate after lots of use in LIFT???

[ZTEC]

Originally Posted by GTsRasta

Was it like that from factory, or did it deviate after lots of use in LIFT???

The lubrication system is a static tube in the valve cover itself with no moving parts just tubing with holes designed to spray Oil on the high lift cam lobe. Mileage or driving style has no effect on it's condition or performance.

[mp3moose]

Very interesting. Kodus to you guys for all the help to the lotus community. I too am hoping to resolve a p1302 issue.

[Balrok]

That sucks....Do you have any pictures of the cames/head to show the 3rd lob and the related wear? I'm also assuming that this is the same on the toyota cars themselves that have the same engine and not 'Lotus' specific? I also agree we'd need to "test" them as well. Then it might have to go to Toyota directly instaed of Lotus....

[ZTEC]

Originally Posted by 4carl

i'm firmly convinced its a lubrication issue what I'm not convinced if its only a misaligned hole. one thing to consider is the cam is very close to the oil hole when the cover is on that makes any difference in the angle smaller. one thing that should be measured is the distance between the holes . do they match the center of the lobes? if in fact its a run of bad covers all cars that were repaired will fail again we need more data ..carl

These are all good points and We did measure the holes in relation to the center left to right and all were within a 16th of center of each cam lobe! The spray angle is reduced as you get closer to the source and crude measurements show a clearance of around 3/4 of an inch from the lobe to the oil hole when the cover is on and even at this distance the oil stream is missing it's mark (center) and not providing the designed lubrication. Definately agree more data is in order !

[tesprit]

Originally Posted by Balrok

That sucks....Do you have any pictures of the cames/head to show the 3rd lob and the related wear? I'm also assuming that this is the same on the toyota cars themselves that have the same engine and not 'Lotus' specific? I also agree we'd need to "test" them as well. Then it might have to go to Toyota directly instaed of Lotus....

http://www.lotustalk.com/forums/show...&postcount=158

[insane]

Originally Posted by Balrok

That sucks....Do you have any pictures of the cames/head to show the 3rd lob and the related wear? I'm also assuming that this is the same on the toyota cars themselves that have the same engine and not 'Lotus' specific? I also agree we'd need to "test" them as well. Then it might have to go to Toyota directly instaed of Lotus....

Yup.... check out my 'link' in post #6 ---^

Originally Posted by ZTEC

These are all good points and We did measure the holes in relation to the center left to right and all were within a 16th of center of each cam lobe! The spray angle is reduced as you get closer to the source and crude measurements show a clearance of around 3/4 of an inch from the lobe to the oil hole when the cover is on and even at this distance the oil stream is missing it's mark (center) and not providing the designed lubrication. Definately agree more data is in order !

Actually, the angle doesn't change with distance. Only the magnitude of error (of missing its mark) changes. Nit-picky point....