more supercharger talk

[truckinwagen]

its the two bolts under the IP that hold the bracket to the front of the block, not sure if they would end up in the timing belt...

but, it is not as big a deal as it could have been, an afternoons worth of wrenching at the very worst to fix it.

[theman53]

I think he was meaning the other lower bolts on the gear side of the pump.

[truckinwagen]

yeah, the pump is mounted solid to the bracket, its just the bracket is loose...

I actually went out to see if the pump came loose, so I pushed on the top of it to see if it would wiggle, and saw the whole bracket move!

its not too bad, I bet I can get to the bolts from below without even pulling the pump out.

-Owen

[truckinwagen]

well, the loose IP bracket was A problem but not THE problem.

I tightened the bolt back down with a lockwasher and blue loctite, but it still acts exactly the same.

I think the next step is to measure the pumps internal pressure and see what it looks like.

-Owen

[arb]

yeah, the pump is mounted solid to the bracket, its just the bracket is loose...

I actually went out to see if the pump came loose, so I pushed on the top of it to see if it would wiggle, and saw the whole bracket move!

its not too bad, I bet I can get to the bolts from below without even pulling the pump out.

-Owen

Didn't the belt try and walk off one end of the sprocket when the plate was flexing ?

[truckinwagen]

nope, thats why I didn't notice it for a while, the belt tracked just fine.

-Owen

[truckinwagen]

well, my new header came in today!

it is a used OBX header, and looks great. no cracks or anything like that(so much nicer than the downpipe I got off the 'Tex)





a schmucks "header reducer" and 2.5-2.25 coupler make the transition to bolt up to the exhaust under the car right now.



I plan to go to a 2.5" exhaust down the road, but all I need to do for that is remove the coupler, and it is all set.

I will grab a new set of gaskets and some clamps tomorrow, and might have it installed by sunday night.

-Owen

[Rabbit on Roids]

well, my new header came in today!

it is a used OBX header, and looks great. no cracks or anything like that(so much nicer than the downpipe I got off the 'Tex)





a schmucks "header reducer" and 2.5-2.25 coupler make the transition to bolt up to the exhaust under the car right now.



I plan to go to a 2.5" exhaust down the road, but all I need to do for that is remove the coupler, and it is all set.

I will grab a new set of gaskets and some clamps tomorrow, and might have it installed by sunday night.

-Owen

please dont clamp your exhaust together, you are better than that...

[truckinwagen]

not the kind of clamps you are thinking about, I am going to use stainless strap clamps, they seal better, and don't deform the tube.

[truckinwagen]

OK, theory time again...

the car has been harder to start recently, not much though and I attributed it to burnt glow plugs.
but there is no real reason for the plugs to stop working all of a sudden.

also, the car is sluggish, smokes more, and EGT's are higher. I attributed all of these to running without boost.

if all of these are assumed to be timing related, it all makes sense.

if the crank pulley was failing, it would take a while(I would hope more than the 250 miles I have on the car) to do substantial damage to the crank nose and act like this. it would also(presumably) happen slowly over a given period of time, not all of sudden like this did.

so here is my idea:
the loose bracket flexed at higher RPM's, effectively loosening the timing belt.
while "loose" during high RPM's the belt skipped one tooth on the crank pulley(retarding timing)
with the retarded timing it wont rev as high, so it wont flex the bracket as much and it did not skip another tooth(thank god)

the advanced nature of the cummins pump did not show up as badly at startup when retarded one tooth, but as it does not advance as far dynamically as the VW one, it showed up when revving.

this should be easy to check for:
set crank at TDC, check pump and cam for TDC marks.
if they are off, then the belt skipped.
re-do timing belt one tooth back on IP and cam, re-tension belt and off I go!

if the cam and pump shot TDC when the crank does, then I will continue with checking internal pressure and advance mechanism.

I will report back with my findings later tonight, after I have a chance to look at the motor.

-Owen

[truckinwagen]

also, I plan on swapping the VW advance spring and shims for the cummins ones and adjusting internal pressure to VW spec so the pump will act more like a vw one.

and I figured out that the noise I thought was clutch chatter on hard starts(and downshifts) turns out to be the rear motor mount, which is so soft that it allows the two brackets to bang into each other when lots of load is applied.

heavy duty rubber mounts are on their way, as well as a poly insert for the offending rear mount(to be installed in the new HD one of course)

hopefully this will also keep my new header from an early demise from excessive motor movement.

-Owen

[truckinwagen]

well, no beans on my timing belt jumping a tooth idea, everything lines up fine.
but it is definitely a timing issue as the car smokes white(lots) when cold.

I got a piece of angle iron to use to get the crank bolt out so I can get a good look at the crank nose and sprocket.

I really hope that it is not the issue, and I still dont think it is, but looking wont hurt anything.

the cam is clearly in time with the crank, but the injection pump I am not sure about, the timing marks could be a notch off, could the pump pulley have jumped a notch?

-Owen

[truckinwagen]

thats what I am hoping happened, even though I would think the crank jumping would be more likley.

I am going to pull the crank pulley to inspect the nose just to be sure though.
I got a piece of angle iron to hold it while I wrench on the bolt.

I will also check what the pump lift is at once I get it running better for future reference.

-Owen

[truckinwagen]

good to know...

hopefully all this will be resolved tomorrow.

[truckinwagen]

well, I advanced the pump one tooth and fired it up, definitely marbley, but started quick and didnt need throttle to stay running like it did yesterday.
I don't remember exactly how it sounded before, but I retarded the pump a little bit(not much) and it sounded better.

took it for a drive and no more stumble at 3000RPM.
I put it in second and floored it and it accelerated smoothly right to 45MPH, which comes to 4880RPM
and when it did stop it felt like the governor, not a timing stumble.
it cruises the bast at about 1800RPM.

for the moment I am not going to pull the crank sprocket(it got warm here, so it is really wet in my driveway) if I can find a garage to work in I might pull it and inspect the crank nose.
but for now, I marked the flywheel and serp pulley so I can compare in a few days to see if they have drifted apart at TDC.

hopefully the new pulley for my alt will come in and I can get the boost back!

-Owen