Doug_B_928

I have been "studying" in preparation for my first attempt at this task (I feel like I'm preparing for an exam). Mine is a 16V (79 5 speed) and most available information is for 32V, but I think I have a handle on the differences. Here are a few remaining points of clarification that I'm hoping you all can help with:

1. The timing belt tensioner spindle threads to the water pump in a location where the threads are exposed to coolant. What is best to put on the the t. t. spindle threads: Loctite 574 or water pump gasket sealant (RTV)?

2. When lining up the cam gears to put on the TB, according to write-ups for 32V cars one should only turn the cams clockwise. However, in the FWSM (p.15-14), under a picture of a 16V engine, there is a note saying to turn the camshaft sprocket "counterclockwise carefully until the teeth match." I'll defer to FWSM but just wonder why they specify counterclockwise on a non-interference engine?

3. Torque spec. for crankshaft bolt: Most write-ups on TB procedure say 217 ft-lbs. However, Chilton's Repair and Tune-Up Guide for 77-81 models says 181 ft-lbs. The 78-80 models Dimensions and Tolerances booklet says 250NM (184 ft-lbs) and someone has hand written "190" in the margin (presumably their rough conversion to ft-lbs). First, just want to confirm that 181 is correct. Also, one write-up on TB procedure put anti-seize on the crank bolt. Is this advisable and, if so, should it be the copper (Optimoly HT) or silver (Optimoly TA) (so far I haven't been able to figure out the difference in when these two are used and just go by FWSM; if anyone can enlighten me that would be great!)?

TIA,

Doug

GlenL

What a great thread to re-open up discussion.

Is your water pump leaking or otherwise suspect? If not then leave it alone.

If you replace it, then put anti-seize on those threads. Use plain, commercial anti-seize as it's much cheaper than the Porsche stuff. Some insist on copper. Silver will be fine, too. Put it on that crank bolt.

The turning of the cams is confusing for me. Mark where they are at the 45 degree offset. And move whichever way they need to go. Once the belt is off they'll snap to a spot that doesn't work for oyu. You've got to turn the cams while holding the belt taught. Then double check the alignment after turing the engine around. I do that a few times just for re-assurance.

Mike Frye

Hi Doug,

I can only comment on one part of your question, but hopefully it will help.

When I was doing my clutch I was in a bind and asked the group what would be damaged if I turned the engine the wrong way.

The only thing anyone could come up with (which made sense to me) was that the cam chain tensioner was designed to apply pressure in only one direction. If the chain is slackened and turned the other way, it could cause problems like binding and maybe even damage the pads or something.

It's normal to have to turn it back and forth slightly to get it to line up where you need it, especially when you're fighting those valve springs but if you're doing a full revolution I think you should stick with the proper direction and not plan on turning it more than you have to in the wrong direction.

Doug_B_928

Thanks, guys.

Glen: My WP is not leaking, but my understanding is that one is supposed to replace it as regular maintenance as part of TB procedure. Is your concern about leaving it alone over broken bolts and, if so, what have you found in your own experience? Good to confirm that you put antiseize on the crankbolt too.

Mike: So, you'd be okay moving it counterclockwise less than one revolution, but if any more than that you'd turn it clockwise, correct?

GlenL

This gets into philosophy of maintenance. I'm in the school of leaving things that are working alone. The water pump is a lot of work to change if it fails. A new water pump costs a lot of money and there's a chance of having a gasket leak, busting a bolt or having a pump fail due to "infant mortality." There is also the chance the the new, tighter belt will make the old one leak. So ya gotta pick your poison. It's part of the "WYAIT" curse.

I should add that I don't replace any rollers unless they aren't turning smoothly. This means potential extra down time getting parts ordered. You can do the same with the WP: see if the shaft turns smoothly and is solid and replace it if it's suspect.

Then again... You can always order everything and send back what you don't use. Check the return policy.

Mike Frye

I don't know if 'OK' is the term. In my case the clutch was partway out and I had no choice but to turn it back the way it came from. I just wanted to know what was in jeopardy of breaking and I wanted to convey what I heard to you.

For the TB/WP job, there's no good reason to turn it more than the valve springs move it in the wrong direction, which is just a few degrees or teeth for the belt. If you need to go more than a few degrees, there's no reason not to rotate it in the right direction.

joehelendetroit

Doug,

If you have not found out already, the timing marks on the cam gears are in different spots for the 16v than the 32v. As you mentioned, most of the how-to's on here are for the 32v (great write up by dwayne), but you need to search for the post from Porken. He has a pic posted that shows where the marks are.

Also, if you plan to rebuild the tensioner, you may want to upgrade to Porken's tensioner. This not as critical as on the 32v engines, but the OEM unit is a real kluge and his is just a better, more durable option.

Bill Ball

I don't know why the early 78-80 spec book says 250 Nm for the crank bolt (referred to as the pulley or v-belt bolt). All the other references, including the 80-84 spec books state 295 Nm (218 Lb Ft). The main pulley changed in 82 to accommodate a ribbed alternator belt, but otherwise everything in that area, including the bolt and its thrust washer, is the same over those years.

Personally I would not put any goop on the bolt. It is not called for anywhere, could change the torque spec and might make the bolt more prone to loosen. Some people like to put antiseize goop on every bolt. The factory did not do this on this bolt. Regardless, I've not seen one of these bolts seize. I've found them as tight as 600 lb ft (people w/o the proper torque wrench seem to way over-estimate 218 lb ft.), but they always come off cleanly and I've not seen any dressed with antiseize.

The water pump is not a scheduled maintenance item. It became sort of customary, at least here, to replace it with each belt, but it is not called for by the factory service procedures. After I acquired my car I did a timing belt at 95K miles. The pump, factory original, was still like brand new (firm bearing still with drag from grease - not freewheeling - no play). I assume some pump failures happened and led to this practice, but we have seen so many reports of problems with replacement pumps, including some new factory pumps, that the pendulum has swung in the other direction for many people, and I've been examining the pumps and not replacing ones that are still in very good shape. But you have to be comfortable with what a good pump looks and feels like.

The prohibition against turning the engine backward is apparently based on the possibility of the timing belt jumping if it is loose. (WSM volume 1, section 15 pages 18d and 104). If I do turn backward a little, I always pull it forward to restore the usual tension state in the belts and chains. Most of the time if I overshoot a timing mark, I just go forward rather than back up, but occasionally I have had to turn an engine backward a bit for one reason or another and don't see that as a problem.

On the early water pump, I don't recall any bolts going through into the water jacket. I could be wrong. The tensioner arm pivot bolt goes through on later pumps (?82 on). [Late edit: I don't think anything went through into the water jacket until the 87 pump where the tensioner arm pivot bolt was replaced with a stud on the pump body. Most of these pumps come with that stud installed already and I don't touch that, but if I did, I'd use some thread sealant.] One of the tensioner bolts is supposed to have sealant on it. See WSM volume 1, section 15, paged 10-11, bolt 14a.

Doug_B_928

Hi All,

This is excellent! It's very interesting to see that different approaches are being used successfully, and that others are unclear about things like the crank bolt torque. Hopefully others will chime in and perhaps we can see what the majority are doing with respect to these questions.

Thanks,

Doug

Doug_B_928

Thanks, Bill.

Some follow-ups:

Great to know. Maybe Porsche later decided it needed the extra torque. Given that all else is equal, I'll torque it to 217.

Excellent point. Has anyone put out some kind of guide for newbies like me to assess the pump?

And for the tensioner bolt WSM calls for Loctite 574. If one does have a WP where the bolt goes through the jacket, do you use Loctite 574 there too?

BTW Bill, your burnout in your avatar is the best I've ever seen. Truly awesome!

Doug

Bill Ball

I have not had any leaks there after using yamabond or common thread sealants.

As to the pump evaluation: The pulley on a fresh pump with new bearings does not spin freely but stops spinning after maybe 1/4 turn. There is essentially no perceptible radial or axial play. The impeller is close to flush with the end of the shaft and the clearance between the impeller and the pump body is less than 0.005 inch (you will have to remove your current water pump to check this). The shaft will not move in and out or laterally. A good used pump's pulley won't be as stiff as a new one, but if the pulley freewheels much more than a turn when you spin the hub, it's on its way out. Everything else should be like new. Anyway, that's how I look at it.

BTW, my first TB job took me 5 days and when I started the car up, oil went all over the floor because I had forgotten to retighten the oil cooler lines on the radiator. Three of the 5 days were spent soliciting advice and pondering over how to remove a broken water pump bolt complicated by a broken tungsten carbide tap. I've done 40+ TB jobs since and not had another broken WP bolt. To avoid broken WP bolts, squirt them with penetrant, let it sit for awhile, rap them sharply on the head with a punch, and break them free with sudden torque, like an impact wrench or light impact gun. Any that do not break free easily but turn with steady resistance are candidates for breaking and should be given more corrosion breaking treatments before being turned further.

Doug_B_928

Terrific information and advice! Thanks, Bill.
Doug

Bill Ball

Dwayne has the tour-de-force of timing belt guides, although his is 32 valve. Some things don't apply to 16 valve (like locking the crank at 45 degrees BTDC), but it's still a monumental guide. WARNING: It's huge!:
http://www.dwaynesgarage.norcal928.o...0Procedure.htm

I provide links to that and some other online guides and add my own learned-the-hardway tips in this document:
http://www.billsworkshop.com/P928S4/...rces-noWSM.pdf

Doug_B_928

Indeed, both documents to which you provided links were required reading in my "exam preparation." What I have done is print out Dwayne's (yes, all 400+ pages) and then insert notes from yours, Pirtle, Sharksink, Chilton, and the FWSM as well as changes relevant to 16V. I then plan to write notes and take pictures as I do the procedure since I know I'll be doing it many more times over the years.

Incidentally, that's from where some of my questions arose. E.g., both Dwayne and Sharksin used "gunk" on the crankshaft before putting on the harnomic balancer (synthetic grease and antiseize, respectively).

Doug

Bill Ball

Dwayne and Dave are very smart guys. I've just never encountered any noticeable corrosion on this bolt or had any problems removing it even when way overtorqued. You may notice a variety of differences in approach like this. I tend to be a minimalist. I do what I think is necessary. Others are way into the "While-You-Are-In-There" approach. Dwayne is one of them. I only go along with some of this. I would always do the oil pan gasket when doing motor mounts and vice versa because the jobs are a serious chore with 100% overlap and you only want to do it once. BUT I don't touch the front main seal or oil pump seals during a timing belt job unless they are leaking. Mine are still original and not leaking after 237K miles. If they begin to leak, I'll get them at the next timing belt. So it goes with antiseize. If there are issues with corrosion or seizing, I'm all for it. Some of this may be geographical/climate. For example, out here in CA I have never seen bad corrosion of the large rear suspension pin, so I just clean it up and put it back in. Others elsewhere report having a horrible time getting the pin out and finding it heavily corroded. So, slathering that seems like a good idea and can't hurt regardless. The crank bolt is a critical item and I don't feel like messing with the factory procedure without some definite reason. Perhaps Dwayne and Dave encountered problems that lead them to do this and they are comfortable that it doesn't adversely affect the bolt torque. I'm not an engineer or professional wrench and wouldn't know.