Seized Intake Cam


16 replies to this topic
  • Diesel_Junkie

Posted April 13, 2009 - 11:32 AM

#1

Yup.
So I over torqued the cam cap bolts and seized the intake cam. I used a torque wrench that was way way out of spec, but I should have known better.

I tore down the engine and that seems to be the only thing wrong. I am at about 150hours on the motor total. Its an 08 WR 450.

I called Engine Dynamics, but they are out of town till the 16th.
A new head is like $560.
I called a few other machine shops but they dont seem to have done this kind of repair before. Anyone know of another shop that has done this before?

What All do I need to complete the job????
New Intake cam.
New cam chain.
New head gasket.
Fixed/new head assembly.
Engine oil change and some new coolant.
Am I missing something?

Also,
While I have this torn down to this level, and at 150 hours.... What else should I consider doing?????
Valve job?
porting?
Any suggestions???

Thanks,

  • William1

Posted April 13, 2009 - 11:41 AM

#2

WilliamsMotowerks
Ron Hamp

  • Demo_Slug

Posted April 13, 2009 - 02:57 PM

#3

very sorry about your cam and head. We should have tore it back down after we had that issue with the cam tensioner bolt.

you need yamaha part # 18P-E11B0-V0-00, its what bubba would do.
http://www.atvscene....t_ride_095.html

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  • Demo_Slug

Posted April 13, 2009 - 03:04 PM

#4

Yup.
So I over torqued the cam cap bolts and seized the intake cam.


how seized is it. is it truly seized.... can you remove the cam from the head?

  • Diesel_Junkie

Posted April 13, 2009 - 03:50 PM

#5

It was bad enough to lock up the engine.

The cam is out of the head and out of the cap. The head and the cap are gaulled pretty good, by a few thou probably. The cam looks bad but actually feels pretty good and smooth, when steel fights aluminum steel usually wins.

There is a chance that resurfacing the head and reusing the cam might work for a while, but I am not sure... I need to leave that to an expert. The preferred solution might also be to deck the cap and then re-bore everything... i dont know though, and most of the machine shops i talked to dont know either.

I made a lot of phone calls and it sounds like Engine dynamics is the defacto place to go for this type of repair, a lot of shops would actually sub out to them. But they are out of town till the 16th. Looks Like I wont be riding for a while... Hopefully I have it back together for the Georgetown enduro on 5/3.

  • rufusz

Posted April 16, 2009 - 01:46 AM

#6

Are you sure it seized because of over tightening of the cam bolts??? I don't believe over tightening could have anything to do with it, because the control surfaces for the cap being so large, that those M6 screws can't over tighten the cam. Hope you understand what I've meant. The torque values for the camshaft bolts are specified only for people who are used to strip bolts out of aluminum or are afraid of tightening it too much.
The sleeve bearings, formed by the head and cap, are converging to the perfect circle by tightening the screws. Simpler: When the screws are not tightened enough, those 2 parts form a shape like an egg, by tightening it they start to form a circle. You can also check it by hand: install a cam and cap, and don't tighten the bolts and rotate the cam by hand. now tighten the bolts and you will notice that the cam turns more easily.

  • Diesel_Junkie

Posted April 16, 2009 - 12:41 PM

#7

It was definitely the cam that was seized, and I am 99% sure it was over torquing. I knew it felt way too tight when I was using that torque wrench, but I kinda trusted the torque wrench would not be off by more than 100%.... Should have known better. I finally went ahead and ordered my own in-lb wrench.

Since the bike will be apart for a while, I went ahead and decided to do everything. Cleaning and re-greasing the whole bike.

doesn't really look like a bike anymore.

Finally got a hold of Engine Dynamics.... they are hooking me up... the repair should not be too costly, and I am having them port and polish too.

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  • BTeam

Posted April 27, 2009 - 06:17 AM

#8

Hey Deisel Junkie, Wondered if you have got your head back from Engine Dynamics... I'm in a similar predicament and have been watching your experiences thus far. Can you let us know the results and what you ended up paying for all their service. I spoke with them a few weeks ago and they seem really nice and more than capable of such repairs.

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  • Diesel_Junkie

Posted April 27, 2009 - 12:20 PM

#9

I dont have it back yet.... I spoke to them a couple times, and expect it this week. They are going to deck the cam cap 0.010" and re-bore the intake side. Cam is apparently ok according to ED. It looks a little messy on the bearing surfaces, but still feels smooth as butter.

Cost for the cam repair should be $120 if I remember correctly. Much cheaper than a new one.. I am going to let them rebuild the head(140hours on it), and port and polish for more $. My cam seems fine, so that saved some money too.

ED was out of town on vacation when I origionally tore the head off the motor, so I talked to a lot of machine shops.... ED was the only shop that seems to have done this before, and knew what they were doing for this type of failure.... In fact a lot of engine (re-)builders I talked to send parts to ED for work.

My actual repair cost is only the $120 plus a gasket, some coolant and motor oil.... but it could be worse if the dammage was worse. Because of the down time I am doing all the other things I should have done a wile ago, repack the muffler, new tires, grease EVERYTHIG, new plastics(on most of it)(color change to white, and a YZ number plate), new fork seals, ground and sanded all the globby welds and parting lines on the subframe and motor mounts. Etc. etc, the list keeps going on. suprisingly this does all take a bit of time. Bicycles can be torn to nothing and rebuilt in about 3 hous, but this is more like 10-20 hours of work for all that stuff.... at least its not as time consuming as rebuilding my rockcrawler from scratch. (I am still a motobike newbie)

  • Demo_Slug

Posted April 27, 2009 - 01:54 PM

#10

They are going to deck the cam cap 0.010" and re-bore the intake side.


so, I guess the cam will sit lower.. you should probably buy a shim kit.

  • Diesel_Junkie

Posted April 27, 2009 - 08:50 PM

#11

ED will send it back with the right shims in it.

  • Demo_Slug

Posted April 27, 2009 - 09:54 PM

#12

ED will send it back with the right shims in it.


new valves?

  • Diesel_Junkie

Posted April 27, 2009 - 11:15 PM

#13

Whatever needs replacing gets replaced. If not, no change.

  • Diesel_Junkie

Posted May 15, 2009 - 11:02 AM

#14

Got the head back from EDCO a little while ago... They did a great job fixing it.
Unfortunately i did not inspect the cam till after I got it back from EDCO with the entire head assembly. As it turned out, I had spun the cam gear, and ended up buying a new intake cam. Only $114 online, but didnt get the cam till last night.

Threw it all together last night and it fired right up... rode around in the dark a bit.... good as new!.

Lessons learned:
Torqe specs are not always trivial.
Use and expensive torque wrench!.

  • Demo_Slug

Posted May 15, 2009 - 11:15 AM

#15

Got the head back from EDCO a little while ago... They did a great job fixing it.
Unfortunately i did not inspect the cam till after I got it back from EDCO with the entire head assembly. As it turned out, I had spun the cam gear, and ended up buying a new intake cam. Only $114 online, but didnt get the cam till last night.

Threw it all together last night and it fired right up... rode around in the dark a bit.... good as new!.

Lessons learned:
Torqe specs are not always trivial.
Use and expensive torque wrench!.


I thought EDCO told you the cam was spun and the valves got bent?

  • Diesel_Junkie

Posted May 15, 2009 - 04:26 PM

#16

EDCO did not know why the valves were bent, just that that were bent... They did not have a cam to compare mine to, so it was up to me to figure out why the valves and piston tried to occupy the same space at the same time.

I did some TT searches and someone had posted pics of where the lobes should be at TDC... My old cam was off by about 15 degrees. luckily it was off by a large enough margin to make it obvious.

I rolled the engine over right after assembly to make sure everything was clear.

By the way... it is much easier to install the valve cover when the AIS system is gone.

And, after the whole teardown and build back up... it is pretty obvious that the bike was designed to not have an AIS on it... AIS is a total afterthough.... the tubes for that do not fit very elegantly on the bike. I highly recommend the eliminator kit.

  • BTeam

Posted May 16, 2009 - 03:44 AM

#17

Thanks for your follow up Diesel Junkie. EDCO has my whole top end, including the cams and I am relying on their "holistic expertise" to fix my problem(s). Last year I began to burn oil and then ended up running low while out on a ride. Limped to a gas stop for oil and narrowly avoided complete tragedy. I know that improperly torqueing my cam retainers led the intake cam loosening and scoring, and hope that the only other damage is only a burned oil ring (the cylinder "looked" good when I took it apart). I have not heard from EDCO yet, but when I do, I'll share my experience as well. Their One-Stop-Shop service, I believe is invaluable. I could not imagine scrambling for a mix-mix match of used and new top end components, not to mention what it would end up costing- still ending in a fruit salad of a machine.
Mountainbiking has been great this season so far, but I can't wait to twist a throttle :doh:




 
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