Balance Belt Broke - Timing is off, How to re-set timing?

Nenw

Nenw

Well-Known Member
Unfortunately, my balance belt blew up this weekend and threw my timing. Only 40k km on them too. Two hours earlier and I would have been 15miles back in the middle of some BLM land with no one in sight. Super grateful. On the drive home I heard some clanking noise in the top end, pulled over and shut her down, and got her towed home. Drove maybe 600-1000ft, the time it took me to recognize the noise, brake from 60mph, and then idled @ about 300rpm for about a minute while I assessed the sound from inside and outside the van.

I dug into it today, pulled the covers, and the broken belt out, and unfortunately, I was not able to rotate the crank to get it to TDC. When I would rotate it would have a hard mechanical stop to it.

I pulled the timing belt and determined that it was my piston hitting the valve. I know this bc when I would change the position of the camshaft, it allowed me to rotate the crank a little further.

So now I need to know how I go about syncing up all component timing without a belt.

Follow my thinking and let me know if I am correct on 2 out of 3 of these.

Crank – pull the glow plug from cylinder 1. Get something long, stuff it into the cylinder and when it gets to the top, look down and ensure the timing marks are aligned. If the marks are aligned and the piston is as high as it can be, then I am golden.
*EDIT* All You need to do is align the timing mark on the pulley to the block if no timing belt is present. Cylinder 1 will be TDC.

Cam – Basing this on the valve adjustment procedure. Pull the rocker cover off and begin to rotate the cam clockwise. Align the timing marks. Check to see that the following valves are closed (ie. Have a gap between the rocker and the valve). Cylinder 1 Exhaust & Intake, Cylinder 2 Intake, Cylinder 3 Exhaust. If these do not have the standard amount of lash then rotate the cam 360 deg, align the marks and check again.

IP – I do not know how to ensure this is in time other than the timing marks being aligned. Is there anything special to this? Does the IP cycle completely with every rotation of the gear?

Also, new belts are on the way. Once I get those I will install them. I can get it started and I will check the compression.

Valves - Worried that I bent a valve. Is there any way of telling with the head on before doing a compression test. Just from visual inspection?

Rocker Shaft and Rocker arms – these look to be in good shape. Nothing is exploded however, I don’t trust they are free of damage. How can I inspect for hairline cracks? As I mentioned there was a bunch of clanking but nothing seemingly exploded on me. Is it possible the valves, rocker, and arms are all good?

Thanks in advance!
 
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Crank- yes; and it's ok to rotate it backwards to ensure the piston is as high as possible (i.e. go beyond and then back to it).
Cam- if #1 int/exh are "on the ramp" rotate 360; if not, you're good.
IP- just align the mark

Shaft/Arms- pull and clean them to inspect visually (I'd use a magnifier).
Valves- measure valve stem heights with rockers removed; a bent shaft/head will prevent it from seating fully causing it to be shorter.
Nenw said:
Is it possible the valves, rocker and arms are all good?
Click to expand...
Sure... not likely, but possible.
 
Perfect guys. Sounds like getting things aligned will be easy enough no concerns there.

Will get the rockers pulled and inspected within the day, valves as well. I head out for a week to visit family before my belts arrive.

Praying the valves are good, the rockers less concerned about. It’ll be a few weeks before a final update but will keep you all in the loop with how things are going.

Thanks.
 
Thanks for the reminder Growler. Should be good. The battery is disconnected so no making that mistake...

I did the initial work on this when I got the van, actually had to redo the work as I installed the plate backwards that separates the timing and balance belt cogs. Pushed everything out out alignment and ended up shredding the accessory belts in about 30 seconds.
That makes this my third time digging into timing on my van, plus I did my buddies almost 2 years ago and his is a daily driver.

I am becoming alarmingly proficient at this. I think from grabbing the first tool to getting the belts removed I think it took me just over an hour.
 
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Assistance, please.

I got the cam to TDC. That was easy.

I think I got the crank to TDC however, the trick of putting something into the cylinder to tell, well, I can't access the piston through the glowplug hole. Looks like there is a little shelf there, perhaps to protect the glow plug element. Do I need to go through the injector port?

I haven't inspected my rocker shaft and arms yet, but I think those are good. I did a quick wipe and nothing stood out.

I do think I've bent some valves. Mind you, I didn't have a good straight edge with me at the time, I just used a 5mm Allen key and laid it over three valves at a time. If the tool rocked then I figured I had differing heights. Well, the tool rocked. I will test again with an actual straight edge tomorrow.

I did some looking around today in the webs and it looks like bent valves can actually be very slight differences in measurements. If anything other than perfectly flat shows itself, is the assumption that something is bent? Would it be worth installing the old timing belt, setting tension, and cranking it over a few times to do a compression test? Should I get a borescope and go through the injector hole and inspect from inside?

I really don't want to have to take this apart!
 
Personally I would try and get a borescope in there. Basically anything you can do to prevent pulling it apart if you don't have to. Thinking good thoughts, because the trails are calling. :)
 
Your hitting the combustion chamber bottom. It’s really hard to get anything down to the top of the piston. Can you not see the timing mark on the balance belt drive gear?
 
@Jgrant0553 the timing marks are all in line. But I need to Confirm I am at TDC with cylinder 1 not at TDC on the alternating cycle. I will try to drop a bicycle spoke in there perhaps that is narrow enough and will be able to weasel its way into the piston if not maybe a derailluer cable will be rigid enough to help me gauge.

@bikerjosh ordered up a borescope abd compression tester last night. Both arrive tomorrow. Sounds like I might have a busy Sunday ahead of me. Going to confirm TDC today. Get the old belt on and tensioned and be ready to do my inspections as soon as the tools arrive.
 
Nenw said:
@Jgrant0553 the timing marks are all in line. But I need to Confirm I am at TDC with cylinder 1 not at TDC on the alternating cycle. I will try to drop a bicycle spoke in there perhaps that is narrow enough and will be able to weasel its way into the piston if not maybe a derailluer cable will be rigid enough to help me gauge.

@bikerjosh ordered up a borescope abd compression tester last night. Both arrive tomorrow. Sounds like I might have a busy Sunday ahead of me. Going to confirm TDC today. Get the old belt on and tensioned and be ready to do my inspections as soon as the tools arrive.
Click to expand...
If all your marks are lined up, including the crank shaft mark then your at TDC. You can’t be in the alternating cycle because you are not turning the camshaft. Does that make sense? The timing mark on the crank is TDC.
 
Nenw said:
But I need to Confirm I am at TDC with cylinder 1 not at TDC on the alternating cycle.
Click to expand...
Sorry, maybe made this seem more complicated than it is.
The injector and the GP are both located inside the pre-chamber. If you can't measure exact TDC it's not a big deal...

The crank timing mark means the #1 piston is @ TDC. Whether that is TDC of the compression stroke vs the exhaust stroke depends on the camshaft's position; and you have to set that separately. The camshaft is correct when it's timing mark is aligned and the #1 valves are off-ramp; both valves fully seated ='s compression stroke.
On a 4 stroke engine there are 4 related piston positions, compression (TDC), power (BDC), exhaust (TDC), intake (BDC). What's actually going on depends on both the piston position and the valve positions.
 
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sorry guys, i had a brain fart on that. I know the concept, have messed with this stuff before but never actually thought too deepy about the correlation of things. Plus totally forgot about compression and exhaust stroke. Add lack of sleep to the mix and brains not too sharp.
Anyway, it's update time.

I'll start with the big news. I got it started and she idles with no issue or clanking noises. Not sure if I'm solid or not though.

I started by removing the rocker, cleaned and thoroughly inspected. I found no trace of cracks, hairline or otherwise.
I ran a straightedge over the top of the valves and it definitely was not flat. I ran a straightedge over 3 valves at a time then would shift over one. In 3 instances I had a high spot on the valves whereas the straight edge would seesaw. Nothing major but noticeable, less than a mm.

I reinstalled the rocker, and the old timing belt so i could run compression. I got everything connected, cycled the engine by hand a few times to ensure there was no interference. Then on a cold engine I got the following readings:
Cylinder 1 - 395psi
Cylinder 2 - 400psi
Cylinder 3- 390psi
Cylinder 4 - 420psi.

Cylinder 3 felt like it hesitated a little to get to 390. Was definitely not as feisty as the other cylinders. Still got there just took a few additional cranks.

Next steps. Going to redo the compression test again however on a properly warmed engine per the manual. This is more for the sake seeing the difference. The numbers are really encouraging though. I will try to drip a little oil down cyclinder 3 as well see if there is change in how quick it picks up and if the # goes up. But as it stands it looks like I am well within spec.

I will also readjust the valves before doing a compression test. It's been a while since I've done one, and that was on a cold engine. Of which I didn't have the cold specs.

Hoping I dodged a bullet here but would really appreciate to hear some thoughts.

Cheers!
 
The numbers look decent.

A little rock when measuring across 3 valve stems wouldn't bother me... I would be surprised if they were all exactly equal; especially on a worn in engine. And I think it is unlikely that you would have bent a valve w/o also cracking/breaking a rocker, the rockers tend to break first because the valve/piston interference is straight on and not at an angle (a lot harder to bend the valve).

BUT, if it was hitting when rotated by hand, then it was hitting when the engine was running.
 
I was pondering this last night.

My first thought is that this was the absolute first job I did myself on the van. However, I'm kind of debunking that bc it's gone 40k km and I've been driving this hard. I think it would have gone much sooner if I would have done something wrong.

This leads me to theory 2 which is, that this was a non-OEM belt, I don't recall what brand but it was sold to me by coombs county back in 2018 when I did the install. The belt was in two or three pieces. Like catastrophic fail.

Also, the engine block behind my timing cover is very dirty. I know that the gaskets around the cover are hard as rocks. I have been in some deep water and have definitely flushed some muck over the top of the block. Thinking this could have also added to things.

Otherwise not quite sure.
 
I’d check to make sure the balance shafts move freely, there shouldn’t be any resistance to them. Also the passenger side balance shaft is actually run by gears through the oil pump. So you might want to remove the oil pump drive gear from the crank shaft and check that the oil pump is moving nicely as well.
 
Those compression numbers look adequate. Maybe re-check your rocker clearances and try again: a slight difference in rocker clearance can have a noticeable effect on compression at cranking speed.
 
Thanks for the heads up on the balance shaft. Was just in there and forgot to check. Will put it on my list.

I did my valves.....boy were some of them really out. This was done on properly warm engine.
Then I also did compression for a second time and got much better numbers. Could have been a hot engine v. cold, or it could have been due to the valves.

Numbers in the parentheses are the original reading.
Cylinder 1 - 420psi (395)
Cylinder 2 - 430psi (400)
Cylinder 3- 400psi - 410psi with some oil dripped into the cylinder. (390)
Cylinder 4 - 430psi (420)

That being said I was just reading the manual and it says to crank with the "throttle valve fully open". Does this mean I should have had the pedal to the metal?

The numbers looking much better aside, I do have two concerns.
First, the valve stems are not perfectly centered on the rockers. Seems concerning.
There seems to be a little bit of a metal rattling sound. Now this could be one of those nothing to see here type sounds. My mind could be worried and the fact that I don't have the timing covers on, perhaps something is rattling around or a little loose. I guess I wouldn't know until buttoning it up. But that being said, i can't recall ever hearing it before but it is very, very slight.

You'll hear it best when the idle raises, then you can clue in on it better.

Wondering If I just button it up after checking the balance shafts or if I should dig into something else.

Thanks again, y'all.
 
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