2.5 Engine Timing

[DavidNoon]

Aloha Everyone. I have a 1998 Boxster, 2.5 engine, 5 speed. My engine had a blown head gasket on cylinder number three. My mechanic and I pulled the cylinder head and replaced the gasket among many other things. We did not have a manual nor did we know about any special tools to keep the camshaft aligned but we did tie off the chains and marked the camshafts before we removed them. We finished our work on the engine and put everything back as it was. The engine started and ran good but we though it was just a bit off so we changed the camshaft timing a little and restarted the engine. It was worse so we did it again. Again it was worse and got it is so far off we can't seem to find it again. We have spent hours trying to get it re-timed but still no luck.

Is there a way to time the camshafts ( 1 - 3) besides just trial and error? The camshaft timing gear stays in place but the camshafts move sometimes when the bolts are loosened and a valve spring pushes them out of the way. When this happens we have to start all over again. The computer seems to keep the engine from firing when we are to far off which doesn't help anything. Surly we are not the first ones to make this mistake. Cylinders 4 - 6 are still at the original settings as we only pulled down one head.

Any Takers on this one?

Mahalo Nui Loa

David Noon

[suburban99]

First I am not a mechanic. But I have worked a bunch on my Boxster (1997 2.5).

Mine had skipped a tooth because cam tensioners were worn out. Timing was off about 1 tooth. CEL was on with various codes.

One thing that helped me out when I first bought the car was manuals...Bentley and 1 I got online for free. Also watch the series of videos

on you tube as a guy is rebuilding a Boxster S engine. 13 or 14 videos IIRC. Here's a link.

Google Boxster manuals for free and you should find the manual...Good Luck.

Edited March 13, 2010 by Loren
made video viewable here

[JFP in PA]

Aloha Everyone. I have a 1998 Boxster, 2.5 engine, 5 speed. My engine had a blown head gasket on cylinder number three. My mechanic and I pulled the cylinder head and replaced the gasket among many other things. We did not have a manual nor did we know about any special tools to keep the camshaft aligned but we did tie off the chains and marked the camshafts before we removed them. We finished our work on the engine and put everything back as it was. The engine started and ran good but we though it was just a bit off so we changed the camshaft timing a little and restarted the engine. It was worse so we did it again. Again it was worse and got it is so far off we can't seem to find it again. We have spent hours trying to get it re-timed but still no luck.

Is there a way to time the camshafts ( 1 - 3) besides just trial and error? The camshaft timing gear stays in place but the camshafts move sometimes when the bolts are loosened and a valve spring pushes them out of the way. When this happens we have to start all over again. The computer seems to keep the engine from firing when we are to far off which doesn't help anything. Surly we are not the first ones to make this mistake. Cylinders 4 - 6 are still at the original settings as we only pulled down one head.

Any Takers on this one?

Mahalo Nui Loa

David Noon

Trying to do this by trial and error is going to be a nightmare. First of all, there are several speical tools required to time (or "allocate" in "Porsche speak") the cams. Below is the "basic" cam tool set, and none of this stuff is cheap ($600-800 for what you see). You also need to be very careful, if the timing goes off just a tad too much, pistons start hitting valves, and you have a new boat anchor..............

Edited March 13, 2010 by JFP in PA

[DavidNoon]

Aloha Again,

I need to clarify something. We are only adjusting the cam timing within the slots on the timing gear. The pistons and valves are not making contact. We have been from one end of the range to the other more than once but the engine still doesn't want to start. At the beginning when we were checking the compression on cylinders 1-3 the engine would actually start and run on 4-6. The compression on 1-3 is good right now. We will check it again today.

How would the special tools help me now? We now also have the Mitchel on-line manual available but it doesn't seem to be much help.

We'll be back out there again today but I question what our results are going to be.

I appreciate anyones help in this matter.

Mahalo Nui Loa

David Noon

[JFP in PA]

The car can run (albeit poorly) with the cam off one tooth on the chain. But you have to remember that these are "interference engines", meaning that at some point in the system rotation, two (or more) components (valves and pistons) enter the same physical space. Obviously, you do not want that to happen at the same time. And, with VarioCam, the actual timing setting is changing while the engine is running. If the cam timing is off too much, the results are disastrous.

The real issue is that you have four cams that all need to be working in concert with each other. I know of only one "proper" (e.g.: the way it is listed in the 13 volume OEM service manuals) method to reset cam timing once the system has been disturbed, and that is using one of these tool sets. I have heard of shops that have manufactured their own version of these, but the issue remains that you have to lock the engine in one position, and then set one cam, lock it down, and then adjust the other cam on the same head to match, and lock it down. Then you repeat the process on the other cylinder bank. If you have ever wondered what the strange green plugs are on the ends of the cam covers, they are for resetting the cams………………

Edited March 13, 2010 by JFP in PA

[DavidNoon]

Up-Date on Boxter Engine Timing

Aloha Everyone,

I really appreciate everyones help in getting my car running. I would like to up-date everyone on the situation. Yesterday we pulled the camshaft cover back off the engine to look at their positions and check the compression on all three cylinders. The compression was good and there has been no contact with valves or pistons. The cams were exactly where they belong as per the pictures of the head and camshafts we took before we pulled it apart. We re-assembled the head yesterday but the engine still will not run.

There is no spark on any on the plugs including 4-6 as well as 1-3. I stuck my computer on the car and it does not read the VIN number any longer. We "reset" the computer during the time we were trying to set the timing on the car. We believe the computer is not allowing the spark. Is there a way to get the computer to get back to normal? Does the computer need to be reset by the Porsche guy here in town and do I need to take the car there or just the computer?

I was thinking the computer might have factory de-fault settings that it could be moved back to by providing the VIN number and connecting the computer to another "programming computer". Everything on the engine is fine, compression is good and the timing is right on. It was probably a mistake to reset the computer. What we did to do this was use the portable computer you plug into the socket on the drivers side to erase the current settings. At the time we thought the computer in the car was getting false signals and was preventing us from getting the timing right.

These problems can lead a person to pull out their hair.

Mahalo

[JFP in PA]

I'm not sure you are going to be happy about this, but, if your cam timing is off too much, the computer will see an incongruity between the crankshaft position and the cam position, which will make the DME confused, throwing off the injector pulse and ignition systems. If the car was able to run, it would promptly throw multiple codes relating to the position sensors; without being able to start it, the DME may not be getting to that point yet.

Do you have a scanner capable of reading "real time" data from the DME? That should capture the position sensors issues as well............ In any case, the computer "resets" by simply removing the + battery cable for about 2 min............

Edited March 16, 2010 by JFP in PA

[smartrepair]

Are you sure the timing is right?

I just remember, that once one bank is set for right timing, the engine needs to be rotated 360º to set the other bank...otherwise the cycle (compression/exhaust etc.) is not correct (it might on reverse now).

Saludos,

Kare

Up-Date on Boxter Engine Timing

Aloha Everyone,

I really appreciate everyones help in getting my car running. I would like to up-date everyone on the situation. Yesterday we pulled the camshaft cover back off the engine to look at their positions and check the compression on all three cylinders. The compression was good and there has been no contact with valves or pistons. The cams were exactly where they belong as per the pictures of the head and camshafts we took before we pulled it apart. We re-assembled the head yesterday but the engine still will not run.

There is no spark on any on the plugs including 4-6 as well as 1-3. I stuck my computer on the car and it does not read the VIN number any longer. We "reset" the computer during the time we were trying to set the timing on the car. We believe the computer is not allowing the spark. Is there a way to get the computer to get back to normal? Does the computer need to be reset by the Porsche guy here in town and do I need to take the car there or just the computer?

I was thinking the computer might have factory de-fault settings that it could be moved back to by providing the VIN number and connecting the computer to another "programming computer". Everything on the engine is fine, compression is good and the timing is right on. It was probably a mistake to reset the computer. What we did to do this was use the portable computer you plug into the socket on the drivers side to erase the current settings. At the time we thought the computer in the car was getting false signals and was preventing us from getting the timing right.

These problems can lead a person to pull out their hair.

Mahalo