BILLisCHILL

i was driving 20mph when my timing belt on my d16z6 snapped on me. Would there be anything wrong with my motor?

scrooge

20mph is pretty low depending what rpm you were at you MIGHTT have toasted your head

BILLisCHILL

pretty low rpm. around 2.5

AccordOn18z

im joking...you dont see a rod hanging out of the block do you

ek-g6

it might be a problem...like bent valves..get it checked out asap..i would look for another z6 head just in case.

BILLisCHILL

would the block be messed up as well? the motor looks perfect so no rod sticking out

qat727

Probably not. If you're lucky, nothing will be busted. If you're not lucky, you've got bent valves and some scratches/divots in your pistons.

For reference, I bought a 95 EX that had the timing belt snap while going 45 mph. None of the valves were bent. You might be lucky.

BILLisCHILL

someone just told me that single cams arent effected by timing belt snapping. can someone verify this?

Crx dude

sohc are effected as well.

Syndacate

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AccordOn18z &raquo;</TD></TR><TR><TD CLASS="quote">im joking...you dont see a rod hanging out of the block do you</TD></TR></TABLE>

I'll take liars for 1000, please?

Ripping a timing belt will not (will NOT) snap a rod.

It'll bend the **** outta your valves though.

It's real simple, if you put a new timing belt on, and it starts up, and runs fine, everything's peachy - if it won't start up, your valves aren't sealing worth of ****, and you probably raped the valves. ().

So what do you do?

A compression test.

If your compression is good accross all cylinders, throw a new timing belt on that bitch and drive away.

If one or 2 (or 4) cylinders is down on comp, you probably *** fucked the head. Also, when you start it - if it's ticking like hell and barely idling it, you probably fucked the head.

BILLisCHILL

damn

stock_honda_coupe

You won't know till you throw a belt on and try to start it.

cimo463

Just do a compression test...That will tell ya every thing ya need to no!

HeikDiesel

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by stock_honda_coupe &raquo;</TD></TR><TR><TD CLASS="quote">You won't know till you throw a belt on and try to start it.</TD></TR></TABLE>

Dont just throw a belt on it. Check for any bent valves since the d16 is an interference engine

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cimo463 &raquo;</TD></TR><TR><TD CLASS="quote">Just do a compression test...That will tell ya every thing ya need to no!</TD></TR></TABLE>

You need a leakdown test for bent valves, not a compession tester

Hardedge

Wow, I'm surprised to see some of these responses. I'm totally ****-retentive and if I so much as snap a timing belt on startup, I'd still be doing a teardown! Oh well, to each his own.

lamboextreme

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BILLisCHILL &raquo;</TD></TR><TR><TD CLASS="quote">i was driving 20mph when my timing belt on my d16z6 snapped on me. Would there be anything wrong with my motor?</TD></TR></TABLE>
How many miles did the timing belt have?

qat727

The D16Z6 is an interference design engine. Any time the pistons are moving independently of the valvetrain, you are subject to bend the valves.

Will you?

Going so well, but you screwed the explanation up. You have to replace the timing belt before you can do a compression check.

How do you intend to check for bent valves without a belt?

Congratulations. You must have more money and time than most of us. I try to avoid unnecessary work where possible.

*know
And no, it won't tell you everything you need to know. I'll try to explain this so people can understand.

In an interference engine, if the valvetrain stops moving while the pistons are still going up and down, the pistons can hit and bend a valve. This is common knowledge.
The valvetrain on a engine has the exhaust valves opening as/after the intake valves close. This leaves a couple of spots where the valves overlap and can each be about half open. Best case scenario is that your timing belt snapped at one of these times, and the piston misses the valve.
According to some of the people here, you should perform a compression check to determine if you bent your valves. This is a good idea. The problem arrives when you try to perform a compression check before you replace the timing belt. If you do this, then the valvetrain will be stationary while your pistons are moving up and down. Does anyone remember why valves get bent in the first place? Lets say you're lucky and the valves aren't in the way of the pistons when you turn the engine over. There's still a hole in at least 2 of the combustion chambers. That's 0 compression on at least 2 cylinders right there. Are your valves bent? Maybe, but we didn't prove anything except that the pistons move up and down.

So, to go about this properly, the pistons and the valves must be moving in sync to properly perform a compression test. For that to happen, the timing belt must be installed and the cam needs to be in time with the crank. So, we install a new timing belt and align the timing marks. Then we can perform a compression check. If you get 0 compression at this point, then you know you have bent valves. Options then? You can pull the head and replace the bent valves, then put it all together with your new timing belt, or you can get a new head or engine. Either way, you can still use your new timing belt.

No you don't.

A leakdown tester is a great thing, but to check for bent valves, it's not necessary. The compression test checks to see how much pressure you are building up in your combustion chamber. If your valve is bent, it won't seat out properly, and you will have a hole in your combustion chamber. If you have a hole, you won't build pressure. If you don't build pressure, you get a 0 or very low compression, and you know there's a problem.

I also contend that it is better to perform the compression check before you start the engine. If your valves are bent, it's possible that they could damage the valve seats if there is enough pressure pushing them back. Without any actual combustion taking place, the chances of this happening are reduced.

Syndacate

Whatever, I don't do compression checks - just throw on a new timing belt, it'll start, or it won't.

It's not ******* rocket science.

HeikDiesel

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by qat727 &raquo;</TD></TR><TR><TD CLASS="quote">

How do you intend to check for bent valves without a belt?</TD></TR></TABLE>


Roll the engine and cams by hand. Put each cylinder at TDC and pressurize it?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by qat727 &raquo;</TD></TR><TR><TD CLASS="quote">

A leakdown tester is a great thing, but to check for bent valves, it's not necessary. The compression test checks to see how much pressure you are building up in your combustion chamber. If your valve is bent, it won't seat out properly, and you will have a hole in your combustion chamber. If you have a hole, you won't build pressure. If you don't build pressure, you get a 0 or very low compression, and you know there's a problem.

</TD></TR></TABLE>

Even then you dont know if its intake or exhaust valves. A leak down tester will tell you that

Luserkid

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Syndacate &raquo;</TD></TR><TR><TD CLASS="quote">Whatever, I don't do compression checks - just throw on a new timing belt, it'll start, or it won't.

It's not ******* rocket science.</TD></TR></TABLE>

Scary enough but im going to agree with him. I snapped my belt before, threw a new belt on compression tested it and drove off. Put a new belt and see what happens, cheapest easiest way to do it. But if by any chance you do have a bad motor...... wanna sell me your crank

qat727

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HeikDiesel &raquo;</TD></TR><TR><TD CLASS="quote">Roll the engine and cams by hand. Put each cylinder at TDC and pressurize it?


Even then you dont know if its intake or exhaust valves. A leak down tester will tell you that</TD></TR></TABLE>

Alright, I stand corrected. If you have a leakdown tester, do that first.

But in all honesty, it really doesn't matter if you know if it's the intake or exhaust valve that's bent before you tear the head off. It's going to have to come off either way. I've just seen several occasions where gunk built up around the exhaust valves has kept them partially open, even when they weren't bent. I have no doubt that a lot of people trying a leakdown test could take this as a mistaken indicator of a bent valve. So, if you go the leakdown test route, you might want to verify that you've dislodged any of the crap around the valve seats before you declare that it's got a bent valve.