When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I got my new timing belt on the car - 1985 model. Everything routed properly (I had it routed wrong when I called you the other night Stan). It all looks good to go, but I have one final question BEFORE I pull the lock tool and rotate the motor. When I got the belt on, I tensioned the tensioner to take out all of the slack. The belt is nice and tight everywhere, except for the area between the left side (driver) cam gear and the oil pump gear. See picture below between gear 3 and gear 4. I am getting over an inch of deflection in this space, but everywhere else is nice and tight. Will rotating the engine with my breaker bar smooth this deflection out across the whole length of the belt? I don't remember this issue from my prior belt jobs.
If your crank is locked then that section of run is not going to see any reaction from the tensioner. Both cams have resistance to motion and more so if the cam is lifting.
Do not forget that correct tension is set with the Cams at No 1 TDC assuming a stock tensioner- no idea where your crank is at the moment- I always install my belt at 45 BTDC but then I have a 32 valve interference motor.
Thanks Fred - it's a 32 valve motor and lock at 45 BTDC. I check tension after rotating 2 times, but don't want to pull the flywheel lock tool to do that if I need to yank the belt and make it tighter in the area between the oil gear and cam sprocket (I don't think I will need to do that, just want to make sure). Some pics of my car:
Ed,
Did you start at the crank routing the belt to the oil pump gear tight to the driver's side cam around the water pump then the passenger side cam which may have to be moved to get the belt on?
Suggest you release the lock tool, check the tension, roll forward to No 1 TDC [very important]- you must set the tension at that spe ific position and nowhere else, then wind the motor forward the two revolutions, final check and/or adjustment.
At No 1 TDC both rotor arms point towards 3 O'clock position.
I suspect you are off a tooth on the left cam sprocket. With the crank locked at 45 deg BTDC (which you are), I would rotate the left cam counter clockwise a bit to add tension to that part of the belt (between the oil pump and left cam) and then check your timing mark alignment. You will have to restring the belt - timing all starts from left cam, so that has to be set properly with respect to the crank. You can rotate the left cam a few degrees clockwise to help get the belt on in that first step.
Ed,
Did you start at the crank routing the belt to the oil pump gear tight to the driver's side cam around the water pump then the passenger side cam which may have to be moved to get the belt on?
Mike - started belt at driver's side cam gear, down to oil pump gear then winding back up eventually to passenger side cam gear. There was slight movement with both cam gears that had to be turned, but nothing unlike what always happens when I do this job. I just don't remember if the slack existed in other jobs and will go away once I rotate the engine. I think it will, but not sure.
Originally Posted by FredR
Ed,
Suggest you release the lock tool, check the tension, roll forward to No 1 TDC [very important]- you must set the tension at that specific position and nowhere else, then wind the motor forward the two revolutions, final check and/or adjustment.
At No 1 TDC both rotor arms point towards 3 O'clock position.
Thanks Fred, well aware of the procedure, but never hurts to repeat it for others playing at home
Originally Posted by Geza
I suspect you are off a tooth on the left cam sprocket. With the crank locked at 45 deg BTDC (which you are), I would rotate the left cam counter clockwise a bit to add tension to that part of the belt (between the oil pump and left cam) and then check your timing mark alignment. You will have to restring the belt - timing all starts from left cam, so that has to be set properly with respect to the crank. You can rotate the left cam a few degrees clockwise to help get the belt on in that first step.
Thanks Geza, that is where I started (left cam gear). The timing is spot on per my 45 degree marks on the sprockets. See pics below.
So are you all saying that the area in question should be tight even before turning the main crank?
The cam profile plays a role in the static belt tension and as you can well imagine if a particular lobe is close to its peak lift the spring reaction is trying to push that cam back down the side of the lobe as it were. If they jump the cam sprocket can easily end up three teeth out. This is basically why when threading the belt we clamp it onto the 5/8 sprocket and put counter clockwise tension on the hex washer to keep the timing we strive for as the belt is engaged on the 1/4 sprocket. Best done with two pairs of hands- I invariably only have one pair!
Remember you are not going to bend any valves even if you happened to be a couple of teeth out which clearly you are not.
Thanks Geza, that is where I started (left cam gear). The timing is spot on per my 45 degree marks on the sprockets. See pics below.
So are you all saying that the area in question should be tight even before turning the main crank?
/QUOTE]
Yes. The segment of belt between the crank, oil pump and left cam sprocket should not have any considerable "slop" in it when the timing marks are set properly. It is not about belt tension, but number of teeth between the crank and cam. Again, rotate the left cam CCW a bit to remove the slop and you'll see the timing marks no longer align properly, probably by one tooth (~7.2 degrees, as I recall).
You should start routing the belt from the crank, past the oil pump to the left cam, then around the WP to the right cam - there should be no "slop" in any segment when the timing marks are aligned. The only slop would be between the right cam and crank, which has zero impact on timing, hence the addition of the tensioner there.
/QUOTE]
Yes. The segment of belt between the crank, oil pump and left cam sprocket should not have any considerable "slop" in it when the timing marks are set properly. It is not about belt tension, but number of teeth between the crank and cam. Again, rotate the left cam CCW a bit to remove the slop and you'll see the timing marks no longer align properly, probably by one tooth (~7.2 degrees, as I recall).
Exactly why Ed needs to remove the crank lock and rotate the crank to No1 TDC. If he has the belt out a tooth it will then be readily apparent but not until..
FYI: 48 teeth on the cam sprocket- 7.5 cam degrees/15 crank degrees per tooth.
Ed, If you pull the crank lock and start to turn the engine as was suggested, what will happen? The crank will start to rotate, the cams won't until the slop is diminished and tension is built in the belt segment between the crank and left cam. Now, you will have an engine with the cams on the timing marks, but the crank no longer in the correct position - 45 BTDC - because you are off a tooth, maybe 2. My apologies on my recollection of the # teeth on the cam sprocket.
OK guys, I think I am starting to see wgat you are saying. Question though, if my timing is out on that left cam, why are my red marks perfectly aligned? How could they line up in this case? (I put them on at 45 BTDC when I first stripped it all down and inserted the flywheel lock tool).
Your left cam to right cam timing is good - you have the correct number of teeth on the belt between the 2 sprockets. Both cams are out of timing with the crank, because you have an extra tooth (or 2) in the belt between the crank and left cam sprocket. Hope this helps.
It does help Geza (and Fred). I pulled the tool from the flywheel, spun crank twice (plus 45) to get to TDC, was out by 2 teeth. Relocked and pulled the belt. Took slack out of space between gear 3 and 4 from above diagram (the initial issue), rotated gears clockwise by 2 teeth to correct position, was able again to get belt on by myself, and pulled the flywheel tool. Rotated again 2X (plus 45 degrees), and timing is now dead on, and no slack anywhere. Indicator is in middle of window on tensioner tool, and tensioner is set. Thanks for the excellent guidance gents.
It does help Geza (and Fred). I pulled the tool from the flywheel, spun crank twice (plus 45) to get to TDC, was out by 2 teeth. Relocked and pulled the belt. Took slack out of space between gear 3 and 4 from above diagram (the initial issue), rotated gears clockwise by 2 teeth to correct position, was able again to get belt on by myself, and pulled the flywheel tool. Rotated again 2X (plus 45 degrees), and timing is now dead on, and no slack anywhere. Indicator is in middle of window on tensioner tool, and tensioner is set. Thanks for the excellent guidance gents.
Ed,
Good result- team work wins every time!
Fitting the belt at 45 BTDC is a no brainer- final checking of the alignment do it at TDC whilst doing the belt tension. Very easy to be a tooth or so out but tensioning the belt by pulling counter clockwise on the 5/8 sprocket is absolutely essential to correct alignment. The beauty of the 32VR cam timing tool is that you can also check the cam timing spot on whilst at the 45 BTDC position but the belt tension has to be done at TDC nonetheless.
9 Vehicles Porsche Helped Engineer that Aren't Porsches
Slideshow: Long before engineering consulting became trendy, Porsche was quietly helping other automakers build everything from supercars to economy hatchbacks.
9 Features and Characteristics That Only Porsche People Understand
Slideshow: Some brands build cars. Porsche builds traditions, obsessions, and a few habits that stopped making sense decades ago but somehow became part of the charm.
This Builder Is Turning Heads With Its Slantnose 911 Creation
Slideshow: A small Polish tuner has reimagined the Porsche 911 Slantnose for the modern era, blending 1980s nostalgia with widebody tuning culture and serious performance upgrades.
Porsche 911 GT3 Artisan Edition Pays Homage to Japanese Culture
Slideshow: Porsche has created a Japan-only 911 GT3 Artisan Edition that blends track-ready hardware with design cues inspired by traditional Japanese craftsmanship.
Porsche Reveals Coupe Variant of the Electric Cayenne With a Fresh Look
Slideshow: Porsche's latest electric Cayenne Coupe blends dramatic styling with supercar acceleration, turning the brand's midsize SUV into a 1,139-horsepower flagship.
Timing belt deflection
). It all looks good to go, but I have one final question BEFORE I pull the lock tool and rotate the motor. When I got the belt on, I tensioned the tensioner to take out all of the slack. The belt is nice and tight everywhere, except for the area between the left side (driver) cam gear and the oil pump gear. See picture below between gear 3 and gear 4. I am getting over an inch of deflection in this space, but everywhere else is nice and tight. Will rotating the engine with my breaker bar smooth this deflection out across the whole length of the belt? I don't remember this issue from my prior belt jobs.
