noise from chain ramp gap?

bolt · 08-12-2008, 08:27 PM

would this gap between the ramp and chain cause a noise that can be mistaken for a collapsed tensioner?

bolt · 07:33 AM

In addition to the above concern-with some background....I bought the car knowing there was a fuel problem (plus it sat for a few years) but i could get it running by pouring gas into the carbs. I had the zeniths rebuilt but the mechanic didnt want to run the car too long because the noise from the left chain box was making a racket like a failed tensioner. So instead of paying another $600-$700 I thought I would try and tackle this armed with the help of the pelican archives and board.

Opening up the left side and I found what looks like a new chain and cleaned up tensioner compared to other pics I've seen on this board. Also I found what looks like a oil oozing from the tensioner-not sure if this is normal. let me know what you think. thanks.

fumanchu · 08-15-2008, 08:38 AM

New chain but old ramps? I think the oozing at the tensioner is not oozing if I interprete the photo correctly. It would be impossible to have oil coming out as the body of the tensioner is whole. The only place oil can come out is where the bolt is or out the top. I just rebuilt mine with the kit from the dealer. Pretty easy really. I also changed my ramps, the one in your picture looks pitted, usually meaning there is some slap.

Your chain must be tight or too small if it wont touch the ramp. Not sure how the chain could be too tight unless the tensioner was rebuilt incorrectly. Maybe I am missing something here.

bolt · 08-16-2008, 09:04 PM

Thanks for your thoughts fumanchu.

I'm waiting anxiously for my new ramps to arrive. I hoping the majority of the gap is due to wear on the old ramps but i think it may be wishful thinking. I'll also order new turbo tensioners and upgrade the idler arms but I'd like to install in phases (process of elimination) to find out what may be causing the gap.

At this point I just want to get it to idle so we can adjust the carbs....

oozing will probably remain a mystery until i remove the tensioner. Will keep you posted.

vntgspd · 08-18-2008, 06:37 AM

Get a flashlight and look at the chain ramp inside the case to the right of the ramp in the photo. The geometry of the chain is off and something inside the case must be "propping" up the chain to get it at that angle. It is possible when someone installed the inner chain ramp they misaligned the bolt and the ramp is sitting on top of the pin end of the bolt instead of locating the pin end in the hole in the chain ramp.

Even a chain that is too short would not cause what you are seeing. The inner sprocket sits down below the crankshaft (i.e. crank pulley) and there is no way the chain can sit above the lower chain ramps. I would not even turn the engine over at this point much less start it!

bolt · 08-19-2008, 10:06 PM

vntgspd,

thanks for the advice. check out what i saw...

now I get to search the board for what would cause this. I hope the chain isn't riding on the crank sprocket in a weird way to cause it to do this. In order for this to happen, it seems as though the chain would have to be on a smaller diameter sprocket.

is it possible the ramps could be installed incorrectly?

any suggestions would be welcome.

....and I originally thought the noise was from a collapsed tensioner...

vntgspd · 08-20-2008, 06:25 AM

It's hard to tell from the picture, but I think my hunch might be right. The angle of the chain ramp inside the case appears to be off. I suspect that when the last person installed the chain and ramps, the pintail bolt that locates the inner ramp did not get installed correctly. If the ramp is sitting on top of the bolt tip on the inner mounting, it would change the angle like what I see in your pictures.

If this is the case, releasing chain tension and checking the inner chain ramp should reveal that the inner chain will move up and down, rotating around the pintail bolt that is installed correctly in the picture.

It looks like you will need to take everything apart and replace the chain ramps and re-time the cam. Given the apparent shoddy workmanship, I would highly recommend replacing both chains, all ramps, and re-timing the cams on both sides. At this time you will also need to carefully inspect the inner and outer chain sprockets for damage. All of this is cheap insurance against a chain failure and subsequent valve/piston damage.

WERK I · WERK I's Garage

Quote:

Originally Posted by bolt

vntgspd,

thanks for the advice. check out what i saw...

Looking at this picture, it appears the chain is not running in line with the chain guide. The chain appears offset....by a large degree in relation to the intermediate shaft sprocket and the cam sprocket. This could be due to a couple of things;
1.) incorrect use of cam sprocket spacers.
2.) double row chain could be on only half of the double row intermediate shaft sprocket. Never tried this, but I guess anything is possible.

I think the engine should be torn down.......all the way. Split case and all. Who knows what else has been down improperly.

dtw · 08-20-2008, 08:13 AM

I see a brown chain ramp in the wrong position. That may be popping the chain up a bit due to incorrect angle on the brown ramp. Replace it with a black ramp and see. Also, pop your right side chain cover to ensure a brown ramp is in place in the appropriate position in there.

bolt · 08-21-2008, 07:18 AM

Thanks vntgspd,werk and dtw...I value your input!

I was just reading chapter 4 'Engine Rebuild Fundamentals' of Bruce Anderson's 'Porsche 911 performance handbook' for some other insights when I read what dtw noticed...."brown ramp goes in the lower right side of the engine" and as you can see, its clearly on the wrong side of the engine. So I'll start there and hope that fixes it but from illustration in the book it doesn't look like the long end of the brown ramp is any longer than the long end of the black ramp. Additionally, like vntgspd noted, the geometry is wrong -most likely due to incorrect installation of the ramp(s) with one end of the ramp floating/riding on top of the bolt that's supposed to secure it.

I hope its not the case of #2 of what Werk said-from what I've been reading, the only way you can put the chain on (without splitting the case) is by rotating the engine on a stand. I understand if the chain is on the sprocket correctly then it can be done.

This weekend I'll open up the right side and post some pics of what I see....I'd do it tonight but I have a six month old baby that I like to spend time with after work

Thanks again.

bolt · 10:32 PM

In addition to one end of the brown ramp "floating" and in the wrong position, it looks like there's a black ramp where the brown one should be.

I searched the boards but wasn't sure....To remove the inner ramps on the right side, do I remove the 4 bolts (forming a parallelogram pattern-left of pic) on the case shown in the pic below? I was guessing you do because but they line up perfectly with ramp angles. Also, is there a better way to remove the outboard ramps besides yanking them out? - I tried to finese them but so far no luck.

sww914 · 08-30-2008, 09:45 PM

Yes. Those bolts secure the chain ramps. They have sealing washers under the heads so order those (washers) as well when you order parts.

OldTee · 08-31-2008, 04:04 AM

Be careful not to drop one of the ramps into the engine. They can be a bear to fish out.

bolt · 09-02-2008, 09:23 PM

sww914 and OldTee thanks for the advice and warning.

Since I'm going to attempt removing the ramps without removing the engine, is there anyway to avoid losing those washers into the case when I pull the ramp bolts?

I read I can use needle nose vise grips on the ramps to make sure those don't drop into the case.

Thanks again for all the help.

dtw · 09-03-2008, 06:30 AM

Quote:

Originally Posted by bolt

sww914 and OldTee thanks for the advice and warning.

Since I'm going to attempt removing the ramps without removing the engine, is there anyway to avoid losing those washers into the case when I pull the ramp bolts?

I read I can use needle nose vise grips on the ramps to make sure those don't drop into the case.

Thanks again for all the help.

The sealing washers on the chain ramp bolts are on the outside of the case, no major risk of dropping them inside.

When pulling the ramps, you could tilt the engine on the stand so that gravity works in your favor. Then they'll fall out into the chain case if you do lose your grip on them.

bolt · 09-07-2008, 11:20 PM

thanks for the advice dtw...can't tilt the engine since I'm gonna try to do this with the engine still in the car.

I'll have some time next weekend to try to complete the ramp removal and replacement.

vntgspd · 09-08-2008, 06:37 AM

Bolt,

At this point you may want to consider dropping the engine, assuming you have a suitable space to work and a good jack. When you get everything together, you will need to re-time the cams and this is possible, but very difficult, when trying to do it in the car.

I can drop my engine in about 1.5hrs by myself without rushing. It may take you twice that time if you have not taken this one out before, but you will save this much time by sorting out the chains, ramps, and timing with the engine on the floor in front of you.

I know it's probably not what you want to hear but the extra investment in time will save you a lot of profanity and timing issues later!

Good luck!

David

fumanchu · 09-11-2008, 06:21 AM

bolt,

vntgspd is right,... dropping the engine is the correct option. but, if you dont, rest assured you can pull the dropped chain ramp out of the bottom of the sump IF you do drop it. Ask me how I know.

good luck

bolt · 09-13-2008, 09:16 AM

vntgsd and fumanchu,

You are correct- not what I wanted to hear but, the truth does hurt sometimes. In any event, I'll have an initial go at it with engine in the car since I just want to try.

Let you know how it goes...

thanks again guys - truly appreciate the wisdom!