1999 Boxster engine failure?
02-09-2010, 12:18 AM
#1
Instructor
Thread Starter
1999 Boxster engine failure?
I recently purchased a 1999 Boxster, manual w 66k mi from a lady for cheap. According to her she came out from the dentist office about a year and a half ago and the car wouldn't start. She had it towed to a local shop and they had a rep from porsche come look at the car and they told her it broke a timing or cam chain and that it would need a new motor at the tune of $14k so she parked it in the garage and left it. Well I had to put a new battery in the car because it was completely caput...2.5 volts. The car turns over 360 degrees by hand. I drained the oil, pulled the oil filter, and pulled the oil pan. Other than some very, very small aluminum chips in the oil, nothing out of the ordinary. I continued on to pull both valve covers and everything looks fine there too. I turned the engine over slightly in both directions and all four cams rotate as they should. So my question is, whats next? I was expecting IMS, but so far everything seems ok from what I can see. I plan on buttoning the engine back up, filling it with oil, doing a compression test, and then seeing if it will fire (after draining all of the year and half old gas obviously). Does anyone else have any other suggestions or ideas?
02-09-2010, 12:31 AM
#2
02-09-2010, 09:30 AM
#5
Instructor
Thread Starter
what else is there to look for if I did drop the engine? The only two things I can think of are making cam holders so I can fully rotate the engine with the covers off to make sure that none of the chain rollers are damaged and dropping the transmission to check the IMS bearing. But at the same time I think I will feel a little silly if I tear this car all to pieces and its just a crankshaft position sensor or something.
02-09-2010, 12:10 PM
#6
Race Director
I recently purchased a 1999 Boxster, manual w 66k mi from a lady for cheap. According to her she came out from the dentist office about a year and a half ago and the car wouldn't start. She had it towed to a local shop and they had a rep from porsche come look at the car and they told her it broke a timing or cam chain and that it would need a new motor at the tune of $14k so she parked it in the garage and left it. Well I had to put a new battery in the car because it was completely caput...2.5 volts. The car turns over 360 degrees by hand. I drained the oil, pulled the oil filter, and pulled the oil pan. Other than some very, very small aluminum chips in the oil, nothing out of the ordinary. I continued on to pull both valve covers and everything looks fine there too. I turned the engine over slightly in both directions and all four cams rotate as they should. So my question is, whats next? I was expecting IMS, but so far everything seems ok from what I can see. I plan on buttoning the engine back up, filling it with oil, doing a compression test, and then seeing if it will fire (after draining all of the year and half old gas obviously). Does anyone else have any other suggestions or ideas?
If you have seen all 4 cams move then the broken cam chain diagnosis by the dealership is wrong.
The metal in the oil can be normal. Depends upon the amount, size of the particles, and the type of metal.
Another check is to remove the oil scavenge pumps, one in each head, and examine them for any metal content.
If the engine spins ok by hand then hook up starter and give the engine a compression test.
Not starting symptom can be caused by many things.
The way the engine doesn't start is significant. If the engine just doesn't crank, well, that can be a bad switch. (My 02 did this and a new switch fixed it.)
It could be a dead battery, bad starter, etc.
If the engine cranks just fine but doesn't fire that's something else. Fuel or spark usually. Or a bad sensor that delivers an implausible signal and the engine controller doesn't know where the pistons are so it refuses to trigger injectors and the spark.
Then if the engine cranks and makes horrible sounding noises, that's another whole another ball game.
With fresh oil in engine verify engine spins by hand at least 2 or more turns in the direction the engine normally spins.
Then spin it by starter. All with plugs out.
If engine spins ok with starter then compression test it.
If compression tests ok... remove oil filter housing and pour oil out into clean drain pan and look for metal. If you find some... there's something internal wrong. Cam chain guide/tensioner failing perhaps.
If you don't find any metal in the oil, refill housing with oil and reinstall housing and filter.
Sincerely,
Macster.
02-09-2010, 01:16 PM
#7
It's not uncommon to see these cars crank but not start after sitting for a while. If you crank the car while holding the gas pedal all the way down it can bring the car back to life. This worked on several occasions at the dealership when cars were towed in for the symptom you are describing.
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02-09-2010, 01:50 PM
#8
Instructor
Thread Starter
Well the car had been running because she had been driving it and got stranded at the dentist. I did replace the battery and will drain the gas but I have not tried to start the car yet as I assumed there were rogue bits of timing chains and who knows what else in the motor originally. Macster, I really like your idea. Its along the lines of what I was thinking only more thorough. As soon as my loctite 5900 gets in I'll put the motor back together and see what I find.
02-10-2010, 06:15 PM
#9
Rennlist Member
The engine needs to be hand cranked -- with spark plugs removed -- at least 2 revolutions. Cams are driven at half crank speed so it takes 2 complete revs of crank for the cams to revolve once.
If you have seen all 4 cams move then the broken cam chain diagnosis by the dealership is wrong.
The metal in the oil can be normal. Depends upon the amount, size of the particles, and the type of metal.
Another check is to remove the oil scavenge pumps, one in each head, and examine them for any metal content.
If the engine spins ok by hand then hook up starter and give the engine a compression test.
Not starting symptom can be caused by many things.
The way the engine doesn't start is significant. If the engine just doesn't crank, well, that can be a bad switch. (My 02 did this and a new switch fixed it.)
It could be a dead battery, bad starter, etc.
If the engine cranks just fine but doesn't fire that's something else. Fuel or spark usually. Or a bad sensor that delivers an implausible signal and the engine controller doesn't know where the pistons are so it refuses to trigger injectors and the spark.
Then if the engine cranks and makes horrible sounding noises, that's another whole another ball game.
With fresh oil in engine verify engine spins by hand at least 2 or more turns in the direction the engine normally spins.
Then spin it by starter. All with plugs out.
If engine spins ok with starter then compression test it.
If compression tests ok... remove oil filter housing and pour oil out into clean drain pan and look for metal. If you find some... there's something internal wrong. Cam chain guide/tensioner failing perhaps.
If you don't find any metal in the oil, refill housing with oil and reinstall housing and filter.
Sincerely,
Macster.
If you have seen all 4 cams move then the broken cam chain diagnosis by the dealership is wrong.
The metal in the oil can be normal. Depends upon the amount, size of the particles, and the type of metal.
Another check is to remove the oil scavenge pumps, one in each head, and examine them for any metal content.
If the engine spins ok by hand then hook up starter and give the engine a compression test.
Not starting symptom can be caused by many things.
The way the engine doesn't start is significant. If the engine just doesn't crank, well, that can be a bad switch. (My 02 did this and a new switch fixed it.)
It could be a dead battery, bad starter, etc.
If the engine cranks just fine but doesn't fire that's something else. Fuel or spark usually. Or a bad sensor that delivers an implausible signal and the engine controller doesn't know where the pistons are so it refuses to trigger injectors and the spark.
Then if the engine cranks and makes horrible sounding noises, that's another whole another ball game.
With fresh oil in engine verify engine spins by hand at least 2 or more turns in the direction the engine normally spins.
Then spin it by starter. All with plugs out.
If engine spins ok with starter then compression test it.
If compression tests ok... remove oil filter housing and pour oil out into clean drain pan and look for metal. If you find some... there's something internal wrong. Cam chain guide/tensioner failing perhaps.
If you don't find any metal in the oil, refill housing with oil and reinstall housing and filter.
Sincerely,
Macster.
02-12-2010, 07:07 PM
#10
Instructor
Thread Starter
Interesting fact. For anyone looking for Loctite 5900 and not wanting to get hosed by spending nearly $15 a tube for 50mL tubes, search for 20166. It's the part number of the 300mL tubes and it's available most places for $30 or less.
02-14-2010, 07:54 PM
#11
Instructor
Thread Starter
Well, pulled the spark plugs and one of them (cylinder number 3) is smashed. I got compressions of 0, 168, 0, 90, 15, and 78 psi. I siphoned the gas out of the tank through the fuel pump but didn't pull the fuel pump or injector relays, so I may have soaked cylinders 4-6, thus resulting the readings of 90, 15, and 78. Looks like an ebay motor may be in order as I am assuming broken valves and damaged heads.
02-14-2010, 09:54 PM
#12
Race Director
Well, pulled the spark plugs and one of them (cylinder number 3) is smashed. I got compressions of 0, 168, 0, 90, 15, and 78 psi. I siphoned the gas out of the tank through the fuel pump but didn't pull the fuel pump or injector relays, so I may have soaked cylinders 4-6, thus resulting the readings of 90, 15, and 78. Looks like an ebay motor may be in order as I am assuming broken valves and damaged heads.
Engine might still be rebuildable if just a piston even a head needs replacing. If block cracked/damaged though unless you're willing to spring for a sleeve job that removes the damaged original cylinder liners and replaces them with liners of some other material and plated with the necessary finish (or made of cast iron with a change in rings and pistons required to co-exist with the cast iron liners).
Trouble with liners is that if they're of a different metal then one has to hope the liner designers have chosen a metal that has the same coefficient of expansion as the block the liners must fit into so the liners don't work loose move around even fail from the heating and expansion and cooling and contraction cycles they'll be exposed to.
Several companies have developed liner fixes for these engines and my limited input is the liner option appears to work ok but I've not yet come across any engines so modified that have substantial miles on them to help determine if the liner solution is a long term ("lifetime") solution or a temporary one. Temporary in this context is not "lifetime" and lifetime is variable based on what the owner considers to be the life of the car.
Not sure how much money you want to throw at this engine in teardown time and labor to determine if engine salvageable. Since you have to pull the engine anyway a few more hours -- if you're doing the work yourself -- removing the heads might be worth it to ascertain the extent of the engine's damage. Start of course with the cylinder bank that has the cylinder from which you removed the smashed spark plug.
You might find a valve head embedded in the piston crown and the valve seats undamaged with some dings/dents in the combustion chamber which might be fillable with proper welding and finishing to obtain the original combustion chamber shape and volume. If the head proves to be crack free and straight and otherwise undamaged it might be reusable with new valves and some touching up.
Sincerely,
Macster.
02-14-2010, 10:23 PM
#13
Instructor
Thread Starter
Yep, when I saw the spark plug I instantly knew I had rogue parts bouncing around in there. Although with the timing chains appearing to be complete I'm curious as to what could of happened. The coolant is low, but not empty, so I wouldn't suspect a cracked cylinder. I've seen low mileage boxster engines for as cheap as $3k. Regardless, I plan on taking a break then dropping the motor and peeking further inside. We have a single point valve cutter at work...don't remember if it's a Serdi or a Newen, that I could throw the heads on if needed. Cutting the seats on that would definitely yield a performance increase over a standard 3 or 5 angle valve job. I've been told that filling in voids in a cylinder head is usually not a good idea unless you plan on replacing the seats as the heat causes all kinds of havoc. But if I have an unrepairable head I'll just start from scratch as list on those is over $2k and I can't get too much of a break on porsche parts at work. And piston sets that I've seen list for $1200. The whole purpose of this car is to be able to track it so however it ends up being fixed, it needs to be fixed right as I don't go easy on my cars. Although, if it's not too severe I'd rather have an engine that I rebuilt than a junkyard motor or one that was re-manufactured by some random company I've never heard of before.
