SR20DET Broken rocker arms, what’s the damage?

[MrTalmus]

Hi guys.

So a while ago I noticed my car started to act wierd. It had loss of power and stuttered alot. So i found out cylinder numer 2 was not working. Fuel and spark was good so I did a compression test:

Cyl 1: 161psi
Cyl 2: 40psi
Cyl 3: 160psi
Cyl 4: 160psi

Tried to add a little engine oil to cylinder number two and it the compression went up to 65psi. I also blowed some compressed air through the cylinder at TDC and could hear air coming through dip-stick hole. So decided rings were bad.

I then decided to start pulling the head off to check the cylinder damage, but after removing the valve cover I noticed both Rockerarms on cylinder 2 was missing and found them in pieces. I’m only missing one of the shims. Gonna look for it in the oil pan.
https://i.imgur.com/Cdx7uut.jpg

I’m guessing that they did not like the Bee-r I installed and therefore broke, but not 100% possitive. I’m still semi-amateur on engines so if any stupid questions asked, please bear with me. Anyways, heres my question.

-Considering lost compression, may the valves then be damaged? Is there any way of diagnosing without pulling head off?
-Is there any other things I should worry about?
-Should I just buy new rockerarms, change oil and try to start it up again? What could go wrong?

In advance, thanks!

[240msh]

Don't start it till you find that other shim. To be safe id pull the head off and inspect everything to prevent any further damage, its fairly easy just make sure you don't screw up your timing. Gasket maker the top of the front cover and on the other side of the headgasket when reinstalling the head, you can pm me for any questions too bro good luck

[MrTalmus]

Don't start it till you find that other shim. To be safe id pull the head off and inspect everything to prevent any further damage, its fairly easy just make sure you don't screw up your timing. Gasket maker the top of the front cover and on the other side of the headgasket when reinstalling the head, you can pm me for any questions too bro good luck

I will of course not start up before I find the last shim. I might try to follow a guide to pull the head off and then give a heads up. That way I can confirm both valves and piston/cylinder damage to be 100% sure. I’ll let you know if I need anything, thanks!

[gaz_moose]

just use a bore scope to look at the top of the pistons for valve contact.

whip the metal sump pan off as you probably have bits in that.

[MrTalmus]

just use a bore scope to look at the top of the pistons for valve contact.

whip the metal sump pan off as you probably have bits in that.

Thanks!

Can I re-use the shims or should I order new ones with the new rocker arms? I’m guessing i’d need to adjust the shims afterwards, but I can start and run the car with the old shims right?

Also, any theory on why there was a loss of compression?

[tb13]

Thanks!

Can I re-use the shims or should I order new ones with the new rocker arms? I’m guessing i’d need to adjust the shims afterwards, but I can start and run the car with the old shims right?

Also, any theory on why there was a loss of compression?

You'll want to measure valve height and properly shim the rocker that was tossed. Re-using the old shim is a bad idea considering it probably wan't the proper thickness.

As for compression loss, more than likely your piston said hello to the valve and bent it, its no longer seating properly and allowing for compression loss. As others said, get a bore scope in there and check it out before moving forward.

[MrTalmus]

You'll want to measure valve height and properly shim the rocker that was tossed. Re-using the old shim is a bad idea considering it probably wan't the proper thickness.

As for compression loss, more than likely your piston said hello to the valve and bent it, its no longer seating properly and allowing for compression loss. As others said, get a bore scope in there and check it out before moving forward.

Alright. I’ll check if I can see anything with a bore scope and see if I can take some good pictures along the way

[MrTalmus]

Okay, so I managed to get som poor quality pictures of the piston. I don't see any "indent/marks" on it, but it seems to be some sort of metal balls or something. Guess I'll have to pull the head off anyways. Looks like some sort of hair on top of the piston as well, don't know how or why.

Is this what it will look like when the piston comes in contact with the valve? I can try take some better pictures if wanted, but quality is gonna be limited by my cheap camera

Edit: Forgot to share link to pictures. https://imgur.com/a/6v1rBym

[tb13]

Okay, so I managed to get som poor quality pictures of the piston. I don't see any "indent/marks" on it, but it seems to be some sort of metal balls or something. Guess I'll have to pull the head off anyways. Looks like some sort of hair on top of the piston as well, don't know how or why.

Is this what it will look like when the piston comes in contact with the valve? I can try take some better pictures if wanted, but quality is gonna be limited by my cheap camera

Edit: Forgot to share link to pictures. https://imgur.com/a/6v1rBymThat certainly does not look good, I can't see any signs of the piston contacting the valve, but those chunks of metal are not supposed to be there. Very possible the piston contacted the valve and a portion of the valve broke which would explain those chunks. Time to pull the head and inspect everything!

Sent from my OnePlus 6

[MrTalmus]

Update:

So I managed to pull the head off. Cylinder wall looks good, piston has 3-4 "small scratches" as seen on pictures.

Valves also looks good, so i don't think there has been any contact between piston and valves. Phew..

I then laid the head on a level surface and dunked the valves in mineral spirits and there was a small leak on the exhaust side, picture is taken 5mins after pouring spirits over the valve. I would guess this is a major problem as the leak would be bigger under pressure.

My theory is that there might be some small pieces of metal or debris between the valve and the valve seats and therefore not allowing the valve to close 100%.

Pictures: https://imgur.com/a/m47x5QA


So, how do I proceed next? Replace the valves or are they refurbishable? If anyone can give me a general direction on what to do, I'll most likely figure out how to do the job. I will try to keep this thread alive until I get the car running again so other people hopefully can find this helpful! I hope my english is understandable by the way.

Thanks

[EFITTZY]

Lap your valve faces and valve seats with valve grinding compound, or take it to a machine shop for a valve job. When you grind your valves and seats it will sink the valve further down into the head, this effectively lengthens your valve and will result in you needing to tip them in order for your lash to be within spec.

I'd opt for the later of the two as your machinist can also check your guides, cam journals, and set lash whiles he's in there.

P.S. Your english is better than a lot of native speakers

[MrTalmus]

Lap your valve faces and valve seats with valve grinding compound, or take it to a machine shop for a valve job. When you grind your valves and seats it will sink the valve further down into the head, this effectively lengthens your valve and will result in you needing to tip them in order for your lash to be within spec.

I'd opt for the later of the two as your machinist can also check your guides, cam journals, and set lash whiles he's in there.

P.S. Your english is better than a lot of native speakers

Thanks for the reply. I think i’ll give it a try to lap them myself. If it turns out to fail, I’ll try to find a machine shop to ship the head to.

Maybe a stupid question, but can I really rule out bad piston rings? Can this little «offset»in the valves make the compression go from 160psi to 40psi? I might be totally wrong, but I feel like there must be a bigger leak somewhere. That beeig said, I haven’t looked at the valves and seats yet.

Is it reccomended to lap all the valves while I’m at it or is this a situation where you would say: If it ain’t broke, don’t fix it?

[gaz_moose]

lap them all. TBH you can just do it yourself. the tool and the paste costs about £20
get the paste that comes in the blue and white tin. one side is course and the other fine fine grit.

put the sucker on the valve put a small amount of paste on the seat of the valve then put it into the guide, then put the stick between your hands and rub it like you were making a fire. you want the valve seat to be a nice uniform grey colour indicating the valve seat is making full contact with the valve.

if the valve was leaking it would stop the cylinder from building pressure. as its basically like having a small hole in it.

If the engine is still I the car I think I would turn it till the pistons were halfway down the bores and pour the same amount of oil down each one and see if your suspect bore drains away first.
if the engine is out the car I would just whip the piston out and have a look at it.

[MrTalmus]

lap them all. TBH you can just do it yourself. the tool and the paste costs about £20
get the paste that comes in the blue and white tin. one side is course and the other fine fine grit.

put the sucker on the valve put a small amount of paste on the seat of the valve then put it into the guide, then put the stick between your hands and rub it like you were making a fire. you want the valve seat to be a nice uniform grey colour indicating the valve seat is making full contact with the valve.

if the valve was leaking it would stop the cylinder from building pressure. as its basically like having a small hole in it.

If the engine is still I the car I think I would turn it till the pistons were halfway down the bores and pour the same amount of oil down each one and see if your suspect bore drains away first.
if the engine is out the car I would just whip the piston out and have a look at it.

Thanks. I've been wathcing some "How to's" on lapping valves, so I'm confident enough to give it a try. Always open to learn something new.

It looks like our local autoshop has both compound and the sucker. Fairly cheap, total of $18.

Pasta (course and fine): https://www.biltema.no/bil---mc/bilverktoy/motorverktyg-motor/kamremsverktoy/ventilslipepasta-fingrov-2000023387

Sucker: https://www.biltema.no/bil---mc/bilverktoy/motorverktyg-motor/kamremsverktoy/ventilslipepinner-2000022774

Engine is still in car. I will finish fixing all these top end problems, if the compression is still low I will presuede to take out the piston. Having the head off or on shouldn't make a difference, right? And the timing chain wouldn't prevent me from turning the crank?

[pacotaco345]

I second lapping the valves yourself, but while you have the valves out I would re-condition them and clean up the combustion chambers, as well as replace the valve stem seals. You can re-condition the valves by chucking them up in a hand drill and spinning them through a piece of scotch brite in your other hand (at least that's what I did)

Make sure to look up a how-to on re shimming the head, there's a few good ones out there if you search. That's the most important step in making sure you don't toss rocker arms again.

As far as the cyl with low compression goes, I'd imagine that was caused by the intake valves not opening and thus not letting any air into the cylinder to be compressed. Obviously you run some risk by not tearing the entire bottom end down and checking the rings, but I'd imagine you're probably safe just to rework the head and call it a day.

I'll add some pictures of before and after re-conditioning valves in a second...

https://uploads.tapatalk-cdn.com/20180915/a147048133af6c383af6f06fb312b2f5.jpg

https://uploads.tapatalk-cdn.com/20180915/be050d76348192fd2f8f91d7c9b06214.jpg

[jr_ss]

When you pull the valves, throw them in a drill and spin it. If the valve faces moves or deviates up and down or at all, the valve is bent. If you have a drill press and a dial indicator you can check for run out on them. Even grinding the valve will tell you if it's bent. I'd check valves before doing any type of lapping.

To remove a piston, the head has to come back off. You cannot remove a posing with the crank in the way and all pistons come out the top, not the bottom. Much more work to pull from bottom.

[MrTalmus]

Hi guys, and thanks for all the help. I've been busy lately with work and have not got the time too work on the car. Last problem I ran in to was compressing the spring valves. I bought a cheap valve spring compressor that didn't fit, but I did som cutting and welding and eventually made it reach down to the valves. But I don't know if I'm using the tool wrong or if it's just a piece of crap. Can't seem to get enough force to compress the spring and the angle of the handle on the tool makes it awkward and impossible to put much force on it without dislocating the tool. Maybe a bad explaination, but here is a pic of the same tool I bought.

https://www.google.no/search?client=ms-android-samsung&biw=412&bih=408&tbm=isch&sa=1&ei=uJOsW5zVIcuvswGq9KD4CQ&ins=false&q=ventilfjær+verktøy&oq=ventilfjær+&gs_l=mobile-gws-wiz-img.1.1.35i39j0j0i24.6491.6793..8058...0.0..0.158. 503.0j4......0....1.lqVtL4LobBo#imgrc=jcU6m3k5mpBV 9M:

Any tips or tricks to maybe make a homemade tool or do I need to buy a expensive one?

[RalliartRsX]

This is the droid you seek
https://www.amazon.com/CAPVSCK-Overhead-Remover-Installer-Compressor/dp/B00AU5LISS

[fitbmx180]

I had to drop my lower and upper pan.. such a pain...i have dual guide rockers forsale to help avoid this problem