Please help, Engine vibration ....

[jcb986]

If this guy can do it so can you. I have rebuilt engines from 6 to V-8's, mostly Chevy engines. My dad had an auto machine shop and I was a grease monkey by 10 years old. Engines are not hard to rebuild...all you need is the right tools, a work place and a good tech manual. Go to this guys website and see how he did it.

http://www.986fix.com/

[Sideways Steve]

Originally Posted by jcb986

If this guy can do it so can you. I have rebuilt engines from 6 to V-8's, mostly Chevy engines. My dad had an auto machine shop and I was a grease monkey by 10 years old. Engines are not hard to rebuild...all you need is the right tools, a work place and a good tech manual. Go to this guys website and see how he did it.

http://www.986fix.com/

Cheers for the link, I have no worries about rebuilding it, my only hold up is getting the parts I need at a reasonable price but like I say, hopefully by the end of today Ill have all the parts bought and on route for reassembly !

The killer is the shipping of the crank and cradle assembly from the USA to Scotland, its over $200 due to the weight

[Sideways Steve]

Well folks results are in, I will post the full explanation of the issue tomorrow but for now, enjoy some pictures !

New parts are all on order and will be here next week so next weekend its rebuild time and boxster back to life ! woohoo !

[Sideways Steve]

[Sideways Steve]

[Sideways Steve]

[Sideways Steve]

[jcb986]

Well first thing first, love the red head on you tabloid, Young, Gifted & Scots. I'm a Scots. No 2, the shot of you standing in the car and knelling behind your car, looks like your twins. Last but not least...that's a spun bearing and the only thing that causes that is, one, engine run low on oil or they put cheap oil or even SAE type. What the heck is all those little springs.

[Pinarelloman]

Mate, that is just great that you are sharing what you are going through & the work required to get it right.
I love my BOX, but would only go so far as pull the engine out.
Any stripping down would be left to experts.
Goodluck & keep us up to date.
Dave from Aussie.

[Sideways Steve]

Well JCB you would think that wouldnt you ???

BUT its actually not a spun bearing ! LOL

What happened is if you look in the lower pictures of the flywheel end of the crank still sitting in the cradle you can actually see its bent just in at the bearing.

The process of self destruction was as follows:

1) Dual mass flywheel failed causing imbalance in the end of the crank.

2) Last main beaing began to wear excessively causing more imbalance and movement in end of crank.

3) Imbalance at high RPM caused crank flex leading to the flywheel/clutch assembly contacting the gearbox bellhousing.

4) Bellhousing contact "kinked" the end of the crankshaft (forces in excess of 1800 Nm acting upon the end of the crank)

5) Clutch was damaged and started to slip

6) Previous Owner took car to garage regarding the clutch issue and strange vibrations at certain RPM

7) Garage incorrectly renewed the flywheel which was found to be faulty and replaced the clutch but DID NOT check for damage to the crankshaft

8) Car ran not too bad for 6 months being driven normally but due to the now kinked crank the bearing wear in the last main bearing got worse and worse.

9) Eventually the main bearing nearest the flywheel failed completely due to the huge forces acting upon it through crank imbalance and the next in bearing began to wear.

10) The now huge amounts of crank movement damaged the new DMF and was allowing the assembly to wiggle about contacting parts of the gearbox bellhousing again whilst all the time wearing the end and second main bearings more and more to the point of complete destruction.

The bottom liine is that the bearings have lost their white metal coating and completely destoyed the already badly damaged crankshaft.

It really is amazing to think that this engine was actually running sweet below 5500 rpm with no nasty noises !!!!!


The bits of spring that you see are from the RMS which was also badly damaged due to the movement in the crankshaft.

Luckily the filter in the oil pump has done its job incredibly well and NO debris has entered the pump or been moved round the rest of the engine meaining that the engine is repairable due to catching this in time !


It does look like a spun bearing at first glance but you can tell its not due to a few things,

Firstly the crank is clearly bent at one end, theres no doubt about that ! theres 0.43mm of runout on it which is crazy !

Secondly the locating tabs on the bearing shells are all intact and not damaged indicatiing that the bearings have not spun in the cradle.

Thirdly the cradle is completely undamaged somehow and there are not any signs of damage to the cups which hold the bearing shells.


I have ordered a new crankshaft and a cradle with main bearings as a complete unit so hopefully when it arrives I can get this beast back together within the next week and begin enjoying my Boxster again as it was designed to be !

[jcb986]

Sideways....

I have never heard or ever seen a flywheel cause this kind of problem. Even during my drag racing days. The rear main may have been starved from oil and overheated, then the crank warped. The bearing does not have to spin and that's a huge plus. Let us know what all you did and what you spent. I'm curious how each tackles this problem of rebuilding a flat 6 and how they may cut a corner to save a few bucks. By the way, what year is the Boxster and what did you get it for $$$$$.

PS. Maybe you should do the assembling in your living room. Built a Lotus engine one time like that.

[Sideways Steve]

Originally Posted by jcb986

Sideways....

I have never heard or ever seen a flywheel cause this kind of problem. Even during my drag racing days. The rear main may have been starved from oil and overheated, then the crank warped. The bearing does not have to spin and that's a huge plus. Let us know what all you did and what you spent. I'm curious how each tackles this problem of rebuilding a flat 6 and how they may cut a corner to save a few bucks. By the way, what year is the Boxster and what did you get it for $$$$$.

PS. Maybe you should do the assembling in your living room. Built a Lotus engine one time like that.

Normally I would agree, however ....

Afetr speaking with the Vibration guy at my work who does the balancing etc on the turbines and then with speaking to a very close friend who is an exceptional mechanic for diesel engines He confirmed that on diesels with failed flywheels he has see major imbalance issues.

On diesels they dont rev fast enough to cause any major issues other than the need to replace the DMF however according to the N&V guy at work an unbalanced 20kg mass on the end of a crank the diameter of the boxster's spinning above 5500 rpm can exert more than 1800 NM of force onto the shaft right at its nearest support point (the first main bearing)

This force is way more than the shaft is designed to take and can very easily flex the shaft to the extent that the clutch cover will contact the gearbox housing.

A rotating mass contacting something hard at those speeds is enough to bend the shaft permanently leading to further damage.

The car has full dealership service history right up to its current milage so the oils etc used are all Porsche recommended items which again makes this scenario even more strange !

We have had a few shaft failures on our turbines here at work due to similar balance issues so its really not surprising that this has happened.

I also had work back yesterday from a local porsche specialist saying that he would not have believed my theory up until late last year when he had a GT3RS come in with similar issues. On stripdown of the GT3 they discovered that the crank had bent due to the flywheel/clucth contacting the housing too !

The car is a late 2000 2.7 Boxster, full dealership history 122,000 miles

Labour has cost me nothing as its done myself and all the parts required to repair have come to just under £800

The car cost me £6500 and currently would sell at a dealership here for £9995 with the spec and options mine has.

So all in Im still not out of pocket really but I really didnt want to be lying under my car after a week of ownership.

Ive managed to save a load of cash due to getting teh crank and its cradle via ebay from a car which had a damaged engine but where the crank was saved. It went right down to the last 7 seconds of bidding but I came through and got it paid for straight away

Assembly will be done in my workshop which is at the rear of the garage its in didnt see the point being clean taking it apart as it was all completely dead anyhow !

All the parts are to be cleaned and checked before re assembly and thats happening this weekend

[crod]

Man you are my new hero.
I am sure you will get all this put back together and running like no other Boxster has ever run!

Cheers!

CR

[Sideways Steve]

well thats the plan, but I have just discovered despite paying top money for a quick shipment from Ohio to Scotland that the seller still has not dropped the package of parts off with UPS yet and hes had it since the 30th March !!!

Its not looking like Ill have her done this month now as Next weekend is the only time Im free due to work commitments so if that parts dont arrive next week then im stuffed for about 3 weeks

[yimmy149]

Wow. Sorry that your having to go through all this, but thankyou for the great set of photos.

There's been a good amount of discussion on this forum about clogged/collapsed valve lifters - what state were yours in?

-james

[jcb986]

International shipping can be a little tricky at times. Well, you know you learn something everyday and this flywheel imbalance is a new on me. But, crap happens. I would definitely have the heads checked for hairline cracks and also check the cylinders. Go have a pint.

[Steve Tinker]

SS
Considering the engine has done 122,000 miles plus the out of balance forces inflicted on the crank assembly, the bores and pistons look in remarkably good condition in the pictures - can you re-use them on the rebuild?
Sounds like you havn't stripped the cylinder heads yet, it will be interesting to see the condition of the lifters, valve guides etc. I'm assuming you are using new chain tensioners, timing chains & IMS bearing when you are assembling the engine.
Keep us all posted and add pictures as the re-build as it goes ahead - lot of interested parties here......

[Sideways Steve]

Originally Posted by Steve Tinker

SS
Considering the engine has done 122,000 miles plus the out of balance forces inflicted on the crank assembly, the bores and pistons look in remarkably good condition in the pictures - can you re-use them on the rebuild?
Sounds like you havn't stripped the cylinder heads yet, it will be interesting to see the condition of the lifters, valve guides etc. I'm assuming you are using new chain tensioners, timing chains & IMS bearing when you are assembling the engine.
Keep us all posted and add pictures as the re-build as it goes ahead - lot of interested parties here......

Yeh, its all a bit odd actually the rest of the engine is fully stripped and EVERYTHING looks to be in perfect condition other than the damage shown in the photos !

I'm planning to reuse pretty much everything that I can and sticking with only using new Bearings, Gaskets and various seals. Basically because everything else looks to be within tolerance and in perfect working order.

This plan may change when I begin putting it back together but we shall see.

The parts from the USA are now on route so hopefully next weekend will be 2 days of rebuilding the heart of the Boxster !

[Sideways Steve]

Well thats all the parts cleaned and ready for re assembly. Everything looks to be in fantastic condition other than the obviously bent crank and wiped out bearings LOL

All was looking good for this weekend but the crank is now stuck with UK customs and its looking like it wont be delivered until next week as there stupidly slow over here

Im gutted as this weekend is my only free one for the next 3 weeks due to work

Looks like she may not be back on the road until may now

[jcb986]

When you getter done we we wanna hear her run. Maybe a u-tube video.

Written message above is a Southern slang, not misspelled.