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Interference motors and types of possible internal damage


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82 replies to this topic

#1 mickytrus

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Posted 22 July 2017 - 12:42 PM

Just wondering about

 

possible damage that can incur when interference motors  snap a timing belt.

 

 

 Valves bend but, what other damage can occur.....

 

I am thinking about lower end damage......

 

Specific example::::       would be     98  EJ22 motors.

 

Thanks, Micky



#2 GeneralDisorder

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Posted 22 July 2017 - 01:00 PM

The intake valves get bent. That's it.

GD

#3 hzimmerman1111

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Posted 22 July 2017 - 03:34 PM

 I have some first-hand experience and just finish repairing my friend's '01 OB EJ251.  Here is my post started this May.

 

http://www.ultimates...ej25-changeout/

 

The belt broke going about 55 mph.  No way do the intake valves survive it but everything else was fine including the pistons.  I got it back on the road with just rebuilding the heads and reassembly with the usual assortment of parts .

 

HZ

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#4 montana tom

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Posted 22 July 2017 - 08:27 PM

Sometimes the exhaust valves get bet as well. Like HZ  said  replace all the valves & reassemble . Haven't seen any piston damage yet.  



#5 wtdash

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Posted 22 July 2017 - 11:35 PM

NOT an Ej22, but bought an '03-ish 2.5 which had a broken T-belt....I was 'told' it was just valves...but @ least one piston was cracked too....probably pics on here....YEP.


Edited by wtdash, 22 July 2017 - 11:37 PM.


#6 GeneralDisorder

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Posted 23 July 2017 - 03:06 AM

That's rare enough that I haven't seen it (on a Subaru). The valve broke completely off which is possible but again super rare. I've personally thrown a 251 belt at freeway speed and that didn't happen.

GD

#7 idosubaru

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Posted 23 July 2017 - 12:50 PM

the few i've seen were lots of bent valves and one friend got lucky with no damage, still driving car now many years since i repaired it.



#8 mickytrus

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Posted 23 July 2017 - 07:00 PM

Sounds pretty encouraging.....

 

 

   In this case, that I am presently dealing with......

 

   Seems like the  Driver's side head.......   Is crapped out....

 

as for the passenger side head I think it is ok..........

 

<<<<<This is why I think this>>>>>>

 

           I tried to put a timing belt on it......

you know.... set up the marks

Arrows point upward on both cam sprockets  and the crank....

 

 Passenger side head, cam spins nicely  when spinning the cam sprocket....

and when arrow is up... there is no tension(no lobes of cam in contact.....

 Driver's side head,   it spins but, it is tight and there is always tension

                                     and ...... impossible to set up the mark on the cam

                                     when piston is moved into position... cam spins out of position...(because the valve is bent and is pushed by piston)

 

SO

       I would like to think that the passenger side head is still ok... that is has not suffered any damage........

       is this as dangerous assumption??????    How about a method to test the valves..........

 

              maybe by compressing air in the cylinder and see if there is leak off?:

 

               Any suggestions?????

               Is there the possibility that the passenger side head is still ok//// it certainly feels ok......

If anybody can chime in..... it would be greatly appreciated......

 

Thanks, Micky



#9 Subaru Scott

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Posted 23 July 2017 - 07:29 PM

It is normal for the drivers side to feel that way, as it is ramping up on valves where the marks line up. I'm assuming your belt did break? You should assume you do have bent valves if so. You can install the belt and do a compression test to find out for sure. Unplug the fuel pump or injectors while testing. You do NOT want to try and run the engine unless your compression check shows good . Like at LEAST 160 psi in every cylinder. Trying to run the engine risks breaking a valve that is bent, resulting in piston/cylinder damage. 



#10 Northfield

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Posted 23 July 2017 - 09:15 PM

I had the toothed rubber belt pop over a notch (not even break) on an older (1969) Fiat 124 Spyder, twin overhead cam 4-cyl., once at highway speed, that engine is high-compression (I think over 10:1) and it buried a valve deep into the piston. When it went "Boom!" my chum had the good sense to instantly push in the clutch.  Basically, was welded in there from the force of impact.  After the descriptive from by buddy who I had loaned it to, and who towed it back to my place, I pulled the head off  (easy enough to do on those cars), took a look at the damage, and dropped in a spare engine from a wrecked Spyder.  A lot easier than attempting to rebuild.  They were small engines (I think about one liter). 

 

You can do an incredible amount of damage with a busted belt (or chain) on an interference engine. Ouch.  I sure would not attempt to turn it over if you plan to rebuild, you risk doing a lot more damage. 



#11 Subaru Scott

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Posted 23 July 2017 - 09:35 PM

You would have found, after deeper investigation, that the opposite happened. The valve dropped, because it was over-revved, or the keepers let go, or it seized. THEN the belt skipped a tooth because of the loose spring/retainer or stuck stem jamming the cam. One tooth off will certainly not bury a valve in a piston.



#12 idosubaru

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Posted 24 July 2017 - 05:58 AM

Passenger side head, cam spins nicely when spinning the cam sprocket....
and when arrow is up... there is no tension(no lobes of cam in contact.....
Driver's side head, it spins but, it is tight and there is always tension
and ...... impossible to set up the mark on the cam
when piston is moved into position... cam spins out of position...(because the valve is bent and is pushed by piston)


You're assumptions are wrong and your engine is fine.
Make sure you're using the correct crank mark, some people use the wrong mark on the crank sprocket, dot instead of the pulley I guess? either way - you seem new to this so you could easily be using the wrong mark.

It is normal for the drivers side cam to be under tension and want to spring out of the 12 noon position because it's compressing the valves at that time. Totally normal. Just carefully move it into position and it will stay there.

Edited by idosubaru, 24 July 2017 - 05:59 AM.


#13 mickytrus

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Posted 24 July 2017 - 12:28 PM

First, thanks for this input in to this situation, definitely invaluable....

 

    The belt did snapped while the vehicle was driving.

The car was under some load going up hills(mountainous traverse)

I was probably driving  40mph or so....

Yeah, I know that sound of belts breaking from non-interference 1.8l's letting go.....

(not really a big deal-have changed them on the side of the road)

So, fortunately I was in a place to pull off on this hill. I had plenty

of tools with me and a jack.   I removed everything down to the

belt(including lower pulley. (Yes, belt snapped)

 

From reading several responses to my post....

 

  

SubaruScott:

 

      You should assume you do have bent valves if so. You can install the
belt and do a compression test to find out for sure. Unplug the fuel
pump or injectors while testing. You do NOT want to try and run the
engine unless your compression check shows good . Like at LEAST 160 psi
in every cylinder. Trying to run the engine risks breaking a valve that
is bent, resulting in piston/cylinder damage.

 

 

This makes alot of sense (if I can install the belt,cause it didn't feel right)

 

 

IdoSubaru:

 

     It is normal for the drivers side cam to be under tension and want to
spring out of the 12 noon position because it's compressing the valves
at that time. Totally normal. Just carefully move it into position and
it will stay there.

 

      What Idosubaru mentions above, is somewhat what I had felt(physically)

while I attempted to install the belt. I did eventually get the driver's cam to sit in this position. 

What caused my hesitation to continue with this roadside repair, was that

when I moved the crank arrow to its position after having both passenger side and

driver's side cams it their respected positions(arrows to notch in back of cover),

the driver's side cam would pop out of position.   I kinda got the feeling that

the process of moving the crankshaft to it's desired location was bumping into

a bent valve(driver's side head) and forcing the driver's side cam to spin clockwise.

 

Thanks, Micky



#14 Gloyale

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Posted 24 July 2017 - 02:15 PM

I've seen teh valve guide crack in addition to bending the valves.  Insepct them carefully before just slapping a new valve in.



#15 idosubaru

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Posted 24 July 2017 - 07:21 PM

Hmmm. I've never seen the piston push a valve like I think you are thinking. But I've always diagnosed bent valves without doing much extra diagnosis to know if that would happen.

+1 to guides, I'm always worried whether their damaged or if a valve can bend a little bit that I can't tell.

Use excellent gaskets and resurface the heads no matter what.

#16 Gloyale

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Posted 25 July 2017 - 02:03 PM

when I moved the crank arrow to its position after having both passenger side and

driver's side cams it their respected positions(arrows to notch in back of cover),

the driver's side cam would pop out of position. 

 

You should be aligning to the hashmarks at the outer edge of the pulleys.  

 

NOT  the arrows, those are for Valve adjustment.

 

Could be part of the problem.

 

But if you broke the belt at speed, I would figure on needing to pull both heads and replace valves.



#17 uniberp

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Posted 25 July 2017 - 02:58 PM

...

when I moved the crank arrow to its position after having both passenger side and

driver's side cams it their respected positions(arrows to notch in back of cover),

the driver's side cam would pop out of position.   I kinda got the feeling that

the process of moving the crankshaft to it's desired location was bumping into

a bent valve(driver's side head) and forcing the driver's side cam to spin clockwise.

 

The trick is to use a breakerbar/socket, not a rachet to pull the belt onto the pulley. If the belt slips the breaker bar will prevent the pulley form advancing from spring force. You can back it up and try again. Once the belt is almost on the pressure will hold the pulley in place so you can re-position the breaker and socket for a better grab to pull it the rest of the way on.


Edited by uniberp, 25 July 2017 - 02:58 PM.


#18 Gloyale

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Posted 25 July 2017 - 03:45 PM

The trick is to use a breakerbar/socket, not a rachet to pull the belt onto the pulley. If the belt slips the breaker bar will prevent the pulley form advancing from spring force. You can back it up and try again. Once the belt is almost on the pressure will hold the pulley in place so you can re-position the breaker and socket for a better grab to pull it the rest of the way on.

 

 

IDK what you mean "pulling" the belt on.  Should be no need for that.

 

Belt should not be stretched AT ALL for installation.  Simply slip it into place with the lower smooth roller and the tensioner not yet installed.

 

Line up the belt to all 3 marks, and then install the compressed and pinned tensioner.  This will be engouh to keep it from slipping yet.  

 

Then install the lower smooth roller, making sure to lift up on the belt to get enough room to install the bolt straight and not crossthreaded.

 

Last step pull pin.

 

No need to stretch or pull the belt with wrenches or whatever you are describing.



#19 mickytrus

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Posted 26 July 2017 - 12:09 PM

Gloyale   thanks!...

 

    This sounds like part of my problem......

 

I will try and install and do compression test......

 

Any recommendations regarding   a type of compression tester...

those plug holes are rather far far away?????

 

 

Thanks! Micky



#20 GeneralDisorder

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Posted 26 July 2017 - 12:14 PM

You don't need to compression test it. Just pull off the valve covers and check the valve lash after correctly timing it. If the lash is really huge on any of the intake valves then they are bent. 

 

GD



#21 AdventureSubaru

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Posted 27 July 2017 - 08:59 AM

Gloyale   thanks!...

 

    This sounds like part of my problem......

 

I will try and install and do compression test......

 

Any recommendations regarding   a type of compression tester...

those plug holes are rather far far away?????

 

 

Thanks! Micky

 

Once you get the belt on properly, you will probably know for sure one way or another as it will either sound normal, or barely run.

 

If it sounds normal, do as GD suggested and check lash.

 

I bought my 98 legacy with a jumped timing belt. I replaced a failing idler and the belt with used parts by way of checking and it eventually started and moved but was really plunky.

 

I ended up getting a cheap used 96 EJ22 and dropping it in. Others just get a set of used heads and the felpro head gaskets (Same as Subaru but for $25 each) and put it all together. If you do the work yourself it wont run you more than a few hundred dollars.

 

But step one is to get a good timing belt on there.

 

www.youtube.com/watch?v=IadwZsnjsj0 Fox's videos are great to get the right visuals. #1 mistake is to mix hash marks and arrows. Use the hash marks only. I turn it over by hand two full revolutions and make sure it all lines up before starting it. ignore the marks on the belt. If the hash marks line up, it's timed.


Edited by AdventureSubaru, 27 July 2017 - 09:00 AM.


#22 mickytrus

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Posted 28 July 2017 - 11:25 AM

much appreciated thanks!

 

checking lash with a feeler gauge??????   

 

How much lash on the valves?        in thousands......   or if you only know MM....

 

Is it the same amount of lash for intake valves  as well as exhaust valves?

 

  Yes, I believe I mixed the arrows with the hash marks.

I could barely see anything but the arrows,  It was night on the side of a desolate road.

Do you have any recommendations as to what I should do to better see these hash marks??????

how to shine up the side of the pully etc. etc. etc.

 

Thanks, Micky



#23 mickytrus

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Posted 28 July 2017 - 11:41 AM

Thanks for the link to Miles Fox and the Subaru Alliance....

 

   So he runs without  timing belt covers.....

 

    What is the consensus on that?  Do any of you run without timing cover?

  And what are you thoughts about not running with timing covers....

 

I myself threw away my timing covers on my EA82's a very long time ago....

and I really like the idea of not running covers. but, that was with the EA82's

 

I would really like know what everybody else is doing.... with the EJ motors and

the timing covers...

 

Thanks, Micky



#24 golucky66

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Posted 28 July 2017 - 11:49 AM

If it's an interference motor, run without covers at your own risk. Knowing that anything getting up there can cause the belt to slip, jump, break, etc and you need valves then. 

 

I've heard some people run without them. I would not on an interference engine. 



#25 matt167

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Posted 28 July 2017 - 12:03 PM

So, I'm working on a '04 WRX that was in a 'not shop' for a head gasket job and timing belt just to get the car back on the road... And the guy working on it was a clueless monkey who claimed to have a clue but, had less than an incling of a clue... He gave up on it partially dissasembled but engine still in car

 

What we learn today is that you don't pull the timing covers and timing belt before pulling the engine, especially if you plan to roll the engine over...

Now essentially the best way out is a new or used long block. Since it was so tired anyway ( EJ207 was the eventual swap )

 

So yeah, Subaru's are also susceptible of incapable mechanics


Edited by matt167, 28 July 2017 - 12:05 PM.





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