Injection Pump Timing Jumped

kulsh

Active member
Joined
May 19, 2014
Location
Michigan
TDI
1998 BEETLE 1.9l
My 1998 Beetle injection pump jumped time. I was very lucky, that belt was very worn it could of been alot worse.

My question is do I just put the injection pump back to the pin hole when I put a new belt on Or is there a BTDC for the pump?

I just bought the car and I didnt know how bad the belt was. I was to busy trying to get it to run.. LOL
 

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
You want the crank at TDC, the locked at TDC #1 and the pump pinned at TDC #1. The cam gear will be loose and the three bolts on the injection pump will be loose, THEN you tension the belt.

But do you know if the cam jumped time at all, or was it just the injection pump?
 

kulsh

Active member
Joined
May 19, 2014
Location
Michigan
TDI
1998 BEETLE 1.9l
Whitedog so right now the pump is 180 degrees out I just have rotate it so I can put the injector locking pin in place?
 

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
At this point I don't know what to tell you. Are you sure the cam is locked at TDC #1? Is the crank at TDC #1? If so, where is the injection pump?
 

Jettascuba

Veteran Member
Joined
May 27, 2009
Location
South Africa
TDI
2002 VW Jetta
Can't see why the IP will jump time, turns easier than the cam sprocket.

I am sure your cam is not locked at TDC. Cam lobes pointing upwards.

In fact, I wonder if anything jumped time...
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
STOP - Keep away from the car until you've done some reading on your new car (welcome to TDI Club!). You have an early model A4 platform with the ALH (VE) motor.
The long process described in the link in Post #4 will explain how the timing must be set.
I'm assuming you had the belt jump the pump sprocket, not the actual pump jumping time.
If you had no interference collisions (valves, pistons, carnage) consider yourself a lucky person.
 

dieseldrive

Well-known member
Joined
Feb 16, 2013
Location
North Carolina
TDI
2001 Jetta
IP's will sometimes jump time before the camshaft because the belt engagement is much more on the cam than the pump (the belt is engaged with many more sprocket teeth than the pump). Have not seen it happen many times on TDI engines, but it used to happen on the IDI engines quite often (if the belt is ran dangerously loose).
 

Lug_Nut

TDIClub Enthusiast, Pre-Forum Veteran Member
Joined
Jun 20, 1998
Location
Sterling, Massachusetts. USA
TDI
idi: 1988 Bolens DGT1700H, the other oil burner: 1967 Saab Sonett II two stroke
The number of teeth engaged is only one (small) consideration. I'd expect that the CRANK jumped and that the fuel pump AND cam didn't jump.

The crank has even fewer teeth engaged in the belt than either the pump or cam, the crank is driving (rather than being driven by) the belt, plus there is tension on the pump side of the crank only. The crank is trying to push the belt towards the cam. There's an intentional reason the slack tensioner is on the lowest tension section of belt.
The pull of the belt from the crank plus the drag on the belt by the cam resistance make the engagement on the fuel pump sprocket quite secure, secure enough that I'd wager it's more effective than the pump pulling on the belt at the cam and only the (relatively) slight spring force of the tensioner on the other side of the cam sprocket.
 

dieseldrive

Well-known member
Joined
Feb 16, 2013
Location
North Carolina
TDI
2001 Jetta
Good points, but I am referring to the percentage of the pulley circumference that contacts the belt, the pulley wraps around more than half of the crank sprocket, nearly half of the cam sprocket, and less than half of the IP sprocket. Keep in mind also that the IP does create significant drag on the belt (takes upwards of 5 hp to turn it at full load).
 

jettawreck

Top Post Dawg
Joined
Aug 2, 2004
Location
Northern Minnesota-55744
TDI
2001 Jetta and 2003 Jetta
The circumference of the pulley/sprocket is what determines how much contact area there is. Slipping/shearing belt "teeth" is very common on the crank sprocket, such as when the tensioner fails.
I know every now and then someone gets "lucky" and a TB slips on the IP, but usually after they get into the job most are not that fortunate.
 
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