Big Problem

[ihuntsum]

Just completed a timing belt, balance belt, rollers, and water pump job on a 85.5 N/A 944. Everything went pretty well - used the flywheel lock. After belt installation and preliminary tensioning removed the flywheel lock, rotated the crankshaft two full revolutions by hand and finished tensioning. Completed the job and tried to start it and no cigar. The engine backfired mildly. Removed the front timing belt cover, manually reset the crankshaft to TDC and now the camshaft is off by about 80 degrees. For the life of me I cannot understand what happened. I do not think I bent any valves because I did not feel any excessive pressure when I rotated the crank manually after installing the belt. I removed the belt today and tried to rotate the camshaft manually and I feel more resistance than I am comfortable with about 10 degrees in each direction. What is my best out here - I would really prefer to not remove the head if possible. What about removing valve cover, loosening/removing camshaft and resetting the cam to the mark on the back of the camshaft housing cover. Please talk simple to me guys - this is the first time I have ever worked on a Porsche engine. Thanks

[John_AZ]

I do not think any posts to follow will offer encouragement. My guess is the cam belt was not fully seated in the crank pully.
What brand of belt did you use? Contitech is the preferred brand.

There is no valve cover and you could loosen the cam belt and put the cam to TDC mark. Then make sure #1 cylinder is at TDC by checking the crank pully marks, the flywheel mark on top of the bell housing and by using a stick in the #1 sparkplug hole and feel for piston at top of rotation. Be fery careful and if you feel resistance STOP. Try to get back to TDC with minimun cam and crank movement. Be very careful.

When you "tried to start and the engine backfired" and "now 80 degrees off" that usually causes valve damage to 2 valves.

Reset the timing and hand crank engine. Again, If you feel resistance, STOP.

If you have a leak down kit (Harbor Freight) you can test with out starting engine.

Best of Luck

John_AZ
1988 924S + 1987 924S

[ihuntsum]

John,

Thanks for the help. I agree - I did not expect a very favorable reply. Right now the crankshaft is at TDC but the cam is off 80-90 degrees. When I try to rotate the camshaft I feel more resistance than I felt rotating the entire engine with belt on. All parts were supplied by the previos owner and the new belt is a Contitech. The engine ran well prior to this work. I agree that the only explanation I have been able to come up with is that the belt jumped some teeth but I find this hard to accept. As a first timer I doubled checked everything. Any help onj repositioning the cam and checking for bent valves without entire head removal would be appreciated.

[Techno Duck]

Reset the car at TDC, both the crank and camshaft. You will feel some resistance when rotating the engine over by hand due to the engine compression, remove all 4 spark plugs and you can turn it over easily.

If the car sounded like a sewing machine when you were cranking it to try and start it, the belt slipped and a few valves may be bent. Not the end of the world, but you will have to pull the cylinder head off.

[speedracing944]

Pull the cam tower. Reset the engine to TDC by the flywheel and reinstall the cam tower at TDC as well. But if the timing jumped 80 degrees while the engine was being rotated or started then there is a good chance some valves are bent. If this is the case don't do as I described but instead remove the head and exchange it with $~380 to many944s for a rebuilt head.

Speedy

[ihuntsum]

The crankshaft is at TDC. The camshaft is 80-90 degrees off and the camshaft belt is removed so when I attempt to move the camshaft to the timing mark I feel more than a little resistance. I would not think that removing the spark plugs would have as much effect as it would if I were rotating the crankshaft. The prevoius replys suggested that I reset both the cam and crank to TDC and that is what I am trying to do but as I said the crank is at TDC and I meet resistance trying to move the cam. I certainly don't know much about this but I would be surprised if I bent any valves because as I said I rotated the crank 720 degrees with the belt installed and felt little resistance. It's possible that I bent some valves when I used the starter but I did not hear anything that sounded like interference. I don't already have bent valves I would hate to do so by forcing the camshaft to TDC. I may have dodged a bullet so far. If I decide to push the issue and force the cam to TDC - any suggestions on how best to do so. What I have done so far is put a pie wrench on the collar behind the rotor but I hate to put much more force on it that way.

[Slam]

Ummm... the crank would show TDC with the cam 180 degrees out, wouldn't it? Don't you get 2 revolutions on the crank for every once around on the cam?

80 to 90 degrees would be cause for concern.

[many944s]

If you aren't excited about pulling the head, you can remove the cam belt, then remove the cam tower. Once the cam tower is off, you can place a straight edge along the tops of the valve stems. If any of the stems are visibly lower than the others, you have bent valves. Now the disclaimer! If the cam tower gasket is still the original gasket, it will be a PITA to clean it off the mating surface of the head (providing you are lucky enough to NOT have any bent valves)... Of course if you do have bent valves the head will be coming off anyway then it's alot easier to clean up! From personal experience I would say you have a couple of bent valves, 4 more than likely.

I'm sure it's not what you wanted to hear, sorry.
As a side note... Even if the valve stems appear to be the same height, this does NOT mean you don't have any bent valves. I have seen valves bend, and be pulled into the seat by the spring so it looks straight! When the spring tension is removed, these valves will tip on the seat enough to see light through!

I'll be keeping my fingers crossed for you! If you do end up with some bent valves, drop me a line and I can help you out with a rebuilt head.

-Nick

[ihuntsum]

Thanks Nick. What all is included in the "cam tower"? Absolutely no experience with overhead cams. I am thinking about loosening the cylinder head retaining bolts almost all the way and then rotating the cam. After I drain the water of course. I would think that the interference between valves and pistons is less than 1/2 inch ? Any thoughts ? What would you do if in this situation ?

[many944s]

The cam tower is the entire assembly that holds the camshaft itself (the whole cast piece that says "PORSCHE" on it). I would release the tension on the t-belt, then remove the cam tower. There are 6 bolts hidden under the threaded metal plugs on the cam tower that you will need a long 6mm allen bit to get to.

Removing the cam tower is not a difficult process, though when removing it care must be taken to not drop the lifters inside it! Once the bolts are removed, the tower can be lifted slightly then "tipped" gently toward the pass. side of the car to help keep the lifters in place. If they do fall out, make sure they are returned to the same position they were originally in when the tower is put back on.

You will also need a new cam tower gasket to re-assemble it (around $10).

Here is the tutorial from Clarks Garage:
www.clarks-garage.com/shop-manual/cam-01.htm

Let us know how it goes!
-Nick

[924Sman]

I think it is off 180....Slam is correct...2 revs per one to the cam. When off 180 you now have the exhaust on the firing mode instead of the intake. Simply put...the cam will match TDC one for intake the other for exhaust so you want the TDC at the correct timing.....Try this...remove the belt and leave the cam where it is then spin the crank off time the same direction and degree. This will allow you to be close enough in time to readjust with the belt and avoiding bending valves. Do remove all four plugs as it helps reduce any compression resistance so if the valves/pistons hit, the resistance will be much greater than the compression. If there is too much resistance when doing this you will feel it....DO NOT force it to spin!! But if no or little resistance is there then slowly spin the crank to TDC along with the cam.

But to be more certain find someone in your locale to help you!!!! You are now in deadmans land. Being this is something you know nothing about you need someone who does. Trying to fix by reading opinions is not the best way to save yourself here.....get an expert on site to work you through this. As you can see many ideas have come about and all or none could be correct, this is like diagnosing cancer from 1000 miles away, you need an expert who can determine exactly where it stands to avoid a possible engine failure.

If you remove the cam housing do use a metal ruler long enough to slip under the followers(aka lifters) when tilting back towards you then hold the ruler under until you can slip the housing off_use a helper to do this. Your help can see the followers as you tilt the cam house and prevent the followers from dropping out. Also be mindful of the housing pins(dowel rod like posts) located on the corners(middle right&left) they are inline with the top of the "P" and "E" in the Porsche embossing. ...So in simple terms you must lift the housing up and back towards you from the fender side to clear the pins. Any resistance ...stop and lift a bit higher to clear the pins. DO NOT bend or cause the pins to be pulled out with the housing. The pins are around 1/4 inch in diameter and stick out of the head about 1/2 inch. DO NOT use a prybar to help aid removing the housing!!!

As you can see from my reply this job now requires some finesse and I highly advise you to get a knowledgable helper before you create more pain and suffering for yourself, this is not a job to play the hero right now!!

Do read up on any material by Porsche to help you along as well as Clark's before you even lift a finger to repair at this stage.

Good luck!!!
Dal

[ihuntsum]

Well I think the camshaft was off 180 degrees due to the crankshafts 2 to 1 ratio to the cam. The crank and the cam are both aligned to their respective marks and the car still does not start. Thus far no one in my area has contacted me and I'm the only Porsche guy I know. If anyone in the area is open to provide assistance let me know. We can probably work out compensation. I think I am going to go to Autozone and see if they have leak down test equipment I can borrow. I know the valves could be bent but I also know that you cannot discount the possibility of coincidence and the failing to start could be related to something else. Any tips on confirming spark to plugs or fuel delivery to injectors?

[924Sman]

If you can get it to crank successfully do so but have the #1 plug out and ground it, crank and look for spark, may be best is a dark area as in daylight it can be tough to see a spark . Next thing I would check is the coil and speed reference sensors. If it fired up prior to this I would say there is fuel and usually can smell it as it will flood the engine. But you can read up on testing the fuel pressure to determine delivery. Could have a faulty fuel relay located on the fuse panel, this too will cause a no start issue. Changing the relay is the least expensive of the choices.

Dal

[earlr85944]

easier to do a compression test:
If you are among the luckiest people on earth, leave the balance belt off, set the marks to the correct positions for crank and cam
install the cam belt and take a compression test, my guess readings will be zero to very low, should be 120psi and above for all 4

you had the cam belt off and were able to rotate the cam: bottom line the valves are bent

you can replace the head or have that one rebuilt, get a hand when reassembling the replacement, after that it will be a piece of cake!

[924Sman]

I agree but the problem on a comp test the engine needs to be at temperature, something out of the question right now. It can be done just not going to get near as accurate result. Need to get the metal hot so it can expand for better compression readings.

And in addition if there is a bad head gasket you can get 0 compression readings and mistake it for a bent valve. I found this out on my rebuild, I thought I tweaked some valves and once the head was removed all valves were fine, the HG on the other hand looked like swiss cheese.

Dal

[earlr85944]

head gasket should be fine, he just did the belts etc. , compression test is good in this case even w/ cold motor, looking for: 0 - DAmm or 140- Yipee

[ihuntsum]

Went to Autozone and they had a compression gauge/ leak down assembly with a compressed air fill fitting. Single gauge that screwed into head in place of spark plug. Set #1 cylinder at TDC and put 90 psi to the cylinder. After >30 minutes the pressure is 75 psi. I take this as a good sign and plan to move to cylinder # 3 - next in firing order I think. Ordered a spark tester from NAPA and it will be here in the am. Thinking about drilling and tapping the cap on the end of my fuel rail to accept a 1/4 inch male pipe thread 0-60 psi gauge? Anyone tried this? Any issues? If I do this I will plug the hole after verifying fuel pressure.

[924Sman]

If you have not seen this perhaps this will help.

Introduction

If you live in the United States and you want to check the fuel pressure on your 944 you have two choices. The first choice is to buy a fuel pressure gauge with metric fittings and metric adapters. However, these are typically very expensive and if you own other cars that are made in the USA, you won't be able to use the fuel pressure gauge on them.

The second choice is to buy a cheap 0-100 fuel pressure gauge which is made to check the fuel pressure on cars made in the US. However, you'll have to make a Metric-to-SAE adapter to be able to use it. The procedure that follows will describe two methods of making an adapter to use an SAE thread fuel pressure gauge.

Most fuel pressure gauges made for US cars use a female 1/4" flare fitting for the gauge. So, this procedure is written assuming that your particular gauge has that fitting. If you find that your pressure gauge has some other size fitting, you'll have to adjust the procedure accordingly.

Tools and Materials


NOTE
When you are looking for a brass fitting, you may find it easier to locate a 1/4" NPT to 1/4" flare fitting. If so, you'll need a 1/4" NPT tap instead of a 1/8" NPT tap. The reason I chose the 1/8" NPT fitting is that when you're drill half way through each side of the adapter and then threading it, it's easier to see the transition from one type of thread to the other with the 1/8" NPT thread on one side.


1 Piece of Round Stock, Aluminum or Mild Steel, 7/8" to 1" diameter (minimum 7/8"), approximately 1" long (Option 2)
1/8" NPT Tap (Option 1 and 2)
12 mm x 1.5 Tap (Option 2)
Brass male-to-male fitting (1/8" NPT to 1/4" flare) (Option 2)
Spare fuel rail cap nut, Porsche P/N 928 110 475 01 (Option 1)
Teflon thread tape (Option 1 and 2)
Option 1


Obtain a spare fuel rail cap nut. You can get one from numerous aftermarket parts vendors for less than $5 USD.
Drill and tap a 1/8" NPT thread hole in the center of the cap.
Apply teflon thread tape to the brass male-to-male fitting and thread into cap nut.
Option 2


Center punch an indent in the middle of the round stock and drill a small pilot hole all the way through.
From one end drill about half way through the piece of round stock using a 10 mm or 13/32" drill bit.
Thread the opening just drilled with a 12 mm x 1.5 pitch tap.
From the other end drill about half way through using an 11/32" drill bit.
Thread the opening just drilled with a 1/8" NPT thread tap.
Go to a plumbing supply store and get a 1/8" NPT to 1/4" flare (male-to-male) fitting and thread into adapter.
You may also want to cut flats on each side of the adapter so you can turn it with a wrench. I cut mind to accept a 17 mm wrench.


Clark's Garage © 1998



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[ihuntsum]

Thanks 924sman - I did see that. I have a 0-60 pressure gauge that should work for fuel. I think I will drill and tap for the 1/4 inch pipe threads. If I mess it up I'll find a replacement. I'm on cylinder # 3 with about 92 psi and it is holding goog so far. About 5 minutes. Does my reasoning sound sane?

[924Sman]

Not real up on it but after 20 mins. if it goes beyond 15 psi there may be an issue but again not certain the rate of leakage.

Dal