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Discussion Starter #1
Hi everyone, I need some help in determining how best to reset the cam sprokets to their proper positions without causing pistons to contact the valves (on the slight chance there is not already damage).

Background: As near as I can tell we had the autotensioner fail on our 1999 which in turn caused the timing belt to jump which in turn caused it to snap which in turn caused the engine to shut off while driving at highway speeds...wife and kids are ok, the van...maybe not. She says she did not hear any loud noises or a tap, tap, tap, etc when the van shut off (pistons hitting valves), but she was more concerned about the traffic bearing down on her so can't be sure.

I plan to install a new tensioner and belt then perform a compression test. I know that most likely the valves are bent and possibly the pistons damaged but since money is tight I though I'd give it try and pray for the best, but I'm not sure how to relalign the cam sprokets.

I searched the forum and could not find any posts regarding the procedure on how to align the timing marks on the cam shafts independently when the timing belt is off. Any help or advice would be much appreciated.

Thanks!
 

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As much as I believe in prayer, I can't think of any way in which you do not have valve and/or piston damage. I think you are waisting your time, you need to pull the heads off and/or look for a good used engine. I do not know of anyone here who broke a timing belt and did not have damage. BTW, how many miles on your '99 when this happended? Good luck. :(
 

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I'm with nwf_snake (on both angles...prayer, plus the valve and/or piston damage). You need to remove the heads. Even valves that do not look damaged may be fractured, and may break further down the road (thus, allowing the engine to "swallow" a valve).

Worse, the pistons that did strike valves may haved cocked in their respective cylinder bores, fracturing or outright breaking the piston skirts. This is some of the possible piston damage nwf_snake alluded to as well.

He's right. The only way to really know for sure is to pull the heads. Replacement engines can me had from an import salvage yard.

OF
 

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Discussion Starter #4
Thanks for the replies...but I am still going to try it so I still need the procedure on how to reset the cams safely...if that doesn't work then I'll replace the heads or junk the van...

It has 123K miles on it...had the timing belt replaced at 105K...but not the autotensioner...this is the only Honda I've owned that I haven't been impressed with, probably my last Honda van
 

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Well, my guess is there is no "procedure". You have an interference engine. By turning the crank or the camshafts without the timing belt on and adjusted, something is probably going to hit. When putting the heads on, you have to have the crank and cams at a certain location and not rotate them until the timing belt is on and adjusted. I do not think there are any alignment marks for you to follow to do what you want to do. There may indeed be a certain crank angle where the pistons are all far enough from the valves that you could freely rotate the cams, but I don't ever recall seeing it in my service manual.
 

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Discussion Starter #6
Ok, well I'll turn the cams slowly and move crank if I feel something hitting when turning cams...

Regarding the piston damage...if this is the case should I be able to feel this while turning the crank by hand if the heads are removed?

I've never removed the cylinder heads before, but I'm an engineer and repair equipment at work regularly so I don't think it's beyond me, if it comes to that I may have some additional questions...this forum is a great resouce; thanks!
 

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I haven't yet studied the crankshaft, but there is a decent chance that there is some position for the crankshaft that has all the pistons retracted down their cylinder somewhat.

The problem you might face is that you don't really have a choice for the positioning of those camshafts. Due to the valve springs, the cams will naturally jump to one of perhaps 4 different positions, each with one or two valves wide open and the rest closed. If you let the camshaft freely rest on the one or two open valves(that is, if the camshaft is released and comes to rest on your open valve), that valve is likely to be trashed.

At risk of repeating others, the time and money you invest in making this engine work is likely to be considerably more than the money you'd invest in a new(used) engine and its installation.

If you want to poke around(and it isn't your primary car), pull both heads and look around. If you have access to a borescope, even for 15 minutes, pull the plugs and have a look.

Read this thread before you proceed.....
http://www.odyclub.com/forums/showthread.php?s=&threadid=86649
 

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mappy,

I've never been sure why everyone always suggests "pull the heads" when the timing belt fails on an interference engine. The simple way to tell if the valves have been damage with a whole lot less work is to remove the valve covers and look for unreasonable valve lash (where valve rockers are not touching the cam shaft). If a valve is bent then it will be bend in its "down" position (that is why the piston strikes it). If that is the case you should be able to see with only slight cam movement that a valve is stuck or hung up. If so then just go from there (determine how many valves are bent / damaged). Another thing to check is to remove the upper timing belt covers for each cam and see where the cam marks are in relation to the marks on the head, then look at the crank and see where the mark is on the balancer compared to the marks on the lower timing cover. Compare to where things should be VS where they are. If you are out at any position by 90 degrees or more expect major damage. If major valve damage then best to either replace the heads (eBay rebuilt?) or used engine. Hope this helps, lots of luck, Russ.
 

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Discussion Starter #9
Thanks everyone...I looked as rberman999 suggested and really the alignment marks on the cam sprokets are both within 2-3 teeth of 2:00 and the crank is approx. at 2:00 at well.

Since they are close to where they should be, I was thinking that I'd approximate the relative position of the alignment marks at the 2:00 position, put the belt on to prevent the springing Superdad noted, then rotate all to TDC alignment marks and make any adjustments from there...by then it may be apparent that the engine is trashed, but if not then I'll try the compression test

...another question, can the engine be run without the accessory belts? That will save me some time while performing the test.

There may very well be many I told you so's after I try it, but at this point there is really not too much more to putting a new belt and tensioner on and giving it a try...if bad then I can use the belt and tensioner on a new engine or sell them to you guys if I decide to junk the van.

Thanks again & will let you know how it goes...
 

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rberman999 said:
...I've never been sure why everyone always suggests "pull the heads" when the timing belt fails on an interference engine...
rberman, I think I can answer that scenario based on a co-worker's misfortune. It's because if there is even any evidence of contact, you'll need to replace that particular valve. You can have a light contact happen, and have the lash check out properly (I've seen this on a Mitsubishi I-4 engine), leave that valve in the head....and then the engine "swallows" that valve when you get it running again (the stem gives way). It can run for a day, weeks, or a month...or more...but the likelihood is high that it will fail, and you have more work to do. The only way to make sure is to pull the cylinder heads, and look.

The biggest possible problem (esp. @ RPM's encountered at the speed you had this difficulty) is your pistons...when the piston strikes a valve, it will probably cock in the cylinder bore, and fracture a piston skirt. The best way to check this is to pull the oil pan. On an Ody, it involves removing a few things (ask me how I know :( ), but once removed, a bottom-end check is not too difficult.

Man, I hate these threads, just like you all do...because we know the issues, we've felt the pain (as gearheads in either our current or previous rides), and wish there were better, more palatable answers when mechanical misfortune strikes. I've endured a failed tensioner scenario (in another make of car), and at the very least it is highly inconvenient.

Hang in there.

OF
 

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0dyfamily,

I fully understand what you are saying. I was talking for "BENT" valves, ones that make major contact with the piston. If in what you describe where a valve can be so slightly bent such that it continues to function then there is likely little to no damage (will you even be able to tell with head pulled?). I'm talking about a belt that breaks with the engine turning at high rpms (1200 rpm or more), the crank will not just stop as the cams will and there will be valve damage (not maybe, maybe not). That you will see from the valve cover removal. By the way I'm good friends with a Honda mechanic and this is how he approaches every broken timing belt he services. Just trying to pass along useful information. Russ
 

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Discussion Starter #12
Just a quick question, when I went out to work on the car tonite I noticed that it was leaking coolant...I had already removed the engine mount bracket the night before and assume that this helps to hold the water pump tight to the engine and since the bolts were removed this is the source of the leak and will be resolved when bracket is put back on...can anyone confirm this?
 

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rberman999 said:
0dyfamily,

I fully understand what you are saying. I was talking for "BENT" valves, ones that make major contact with the piston. If in what you describe where a valve can be so slightly bent such that it continues to function then there is likely little to no damage (will you even be able to tell with head pulled?). ...
Russ, I'm not much of an expert...I had a pretty indepth discussion with a mechanic who handled a number of these when I was stationed in Nor Cal, including my buddy's Eclipse. That was his take on it...check, because valves aren't made to sustain that sort of stress where they are pushed laterally and vertically at the same time, even in the smallest amount where they end up springing back to on-center with the valve guide and valve seat.

You're right, I'm with you on that one...I'd believe you could get a number of contacts where the evidence may not be evident at all by just looking at the valve, but the aluminum piston crown will have a telltale crescent-shaped dent. Replace that valve with a fresh one, lap it, adjust. Check the piston skirts, put the oil pan back on.

I guess you could leave the heads on, use your technique of checking lash (I like that...very clever), and use a borescope (like a Hawkeye, or something similar) to check the piston crowns. Would save a lot of work, for sure.

Man, I'm just glad it isn't me. Keeping my fingers crossed, and hoping his results match the scenario you describe. That would be best!

Don't mean to sound like a know-it-all...I've been humbled before, Bill Buckner style, and you have a Mickey Mantle batting average for getting the right information.

OF
 

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You should be able to run the van without accessory belts.

Even at idle(not 2000rpm highway speed), the engine would have way more than enough momentum to do several revolutions of damage with both those expensive valvetrains completely stopped.

Why wasn't the autotensioner replaced back at 105k?
 

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Discussion Starter #15
I replaced the timing belt myself back at 105K and the service manual does not call for replacement of the tensioner just re-compressing it, which I did per the procedure called out.

...of course now I obviously wished I had replaced it and would recommend that for all who perform their own timing belt replacements in the future you replace the tensioner!

I was able to get all of the alignment marks to TDC following the method I noted in an earlier post and had to adjust the rear cam about 2 teeth to get to the alignment mark and the front about 1 tooth, I never felt anything hitting or any major resistance when turning the crank with the timing belt on (other than the spring resistance from the valve rockers)...so I'm cautiously hopeful. I plan to put everything back together and fire it up on Saturday...will let you all know how it goes.

BTW, I've attached a picture of the ends of the snapped timing belt. There was about 2 cups of shredded timing belt bits I pulled out after removing the covers...it must have been slipping (walking?) for awhile? Or could it have shredded that much when it failed?
 

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Big question...was the belt still on the pulleys when you removed it, and how did it snap? Did it fail lengthwise, with the belt cogs still engaging the teeth on the sprockets? If it was, and you were only a few teeth off, you might be very lucky here, with no damage.

If it fell off with the engine at the RPM used to maintain speed on that freeway, well that would be the less desireable to the undesireable scenarios.

The timing belt doesn't "walk" like a V-belt may "slip". If it skips a tooth, the car will not run well. A couple teeth, and it may not run at all.

We're all pulling for you.

OF
 

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Discussion Starter #17
It was strange, the belt had lost about 1/2 of it's width in some areas as if it was off to the side of the sprokets and had been rubbing on something.

It snapped lengthwise and if memory serves correctly was compleletly off of the rear cam sproket, partially on the front and bunched up around the front side of crank shaft. As I mentioned earlier there was about 2 cups worth of timing belt bits...

The wife is making me take the night off tonite to go out to dinner but I should have a result on Saturday, I assume it will be readily apparent if there is an issue with the engine after I have it back together and start it up?

Well thanks again for your advice and well wishes...
 

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Hello Mappy,

My son just went through this with his BMW. In his case the belt slipped. The mechanic aligned everything to the proper marks, then ran a compression check. The compression was 0 psi indicating damage.

The mechanics son was looking for a parts car, so my son negotiated a deal and sold the car to him.

When you get things lined up, try doing a compression check.

Tom
 

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Discussion Starter #19 (Edited)
Well we got everything back together fired up the car and...

...everything seems to be fine! It runs like it did before, drove it for about 15 minutes brought it up to 4000 rpm with no issues. So, who wants to buy a 99 Odyssey?!

Seriously though, I am concerned about latent issues based on some of the comments here, what I certainly don't want to have happen is to have the wife and kids driving down the highway and the valves break, engine blow up, cut out, etc and put them in harms way.

So I guess at this point my question is what can happen from here? If there is a future issue what most likely will it be and what could happen?

My inclination is to trade the van in on something else, but hate to spend the money unnecessarily...but the family's safety is paramount. Any thoughts?

Thanks again for everyone's help, it was intergral to getting back up and running!

-M.
 

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Get a cell phone for the wife if she doesn't already have one.

No need to trade a fully functional van. Even if its a total engine loss tomorrow its not like you are out much.
 
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