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CEL: Engine stumbling stuttering and wanting to shut-off

 
Old 07-11-2019, 07:29 AM
  #61  
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Originally Posted by Rdrcr View Post
Dundon Motorsports has confirmed the issues my car is experiencing. They will be performing a leak-down and compression test. I'm hoping to get news tomorrow.

Fingers crossed for something simple/inexpensive...

Mike
Best of luck!
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Old 07-11-2019, 11:11 PM
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Originally Posted by 808Bill View Post
Best of luck!


See below...

Mike
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Old 07-11-2019, 11:13 PM
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Zero compression, cylinder #1.

After checking the engine with a borescope, they believe the intake valve spring for cylinder #1 is broken. The engine will need to be removed to fix the issue. I'm awaiting my quote for the repair on Monday.

The good news...no bore scoring and everything else seems to be in great condition!!!

A broken intake valve spring, or any valve spring in general for these engines seems pretty uncommon.
However, I have read of a couple examples...

I'm assuming the engine does have to be removed to repair a valve spring, correct?
Do the heads need to be removed for this repair?

Any thoughts? Suggestions?

Mike
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Old 07-12-2019, 12:45 AM
  #64  
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Originally Posted by Rdrcr View Post
Zero compression, cylinder #1.

After checking the engine with a borescope, they believe the intake valve spring for cylinder #1 is broken. The engine will need to be removed to fix the issue. I'm awaiting my quote for the repair on Monday.

The good news...no bore scoring and everything else seems to be in great condition!!!

A broken intake valve spring, or any valve spring in general for these engines seems pretty uncommon.
However, I have read of a couple examples...

I'm assuming the engine does have to be removed to repair a valve spring, correct?
Do the heads need to be removed for this repair?

Any thoughts? Suggestions?

Mike
0 compression/broken valve spring, interesting. It's not very common but does happen from time to time.

I can hear a 0 compression from listening to the engine spin on the starter before cranking. The starter speed will noticeably increase for an instant as the effected cylinder is suppose to be on compression stroke. I then do the compression test only to verify which cylinder it is, then do a leak down test to determine where the lost compression is going, (ie intake valve or exhaust valve or crankcase/piston.)

With the right tools , the heads don't have to be removed or the engine removed. Just the cam cover, cam, lifters, and lifter carrier..

I prefer to do it with the engine still in the car (just lower the effected side), but a lot of techs prefer to drop the whole engine/trans assembly..
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Old 07-12-2019, 01:02 AM
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Originally Posted by Porschetech3 View Post
0 compression/broken valve spring, interesting. It's not very common but does happen from time to time.

I can hear a 0 compression from listening to the engine spin on the starter before cranking. The starter speed will noticeably increase for an instant as the effected cylinder is suppose to be on compression stroke. I then do the compression test only to verify which cylinder it is, then do a leak down test to determine where the lost compression is going, (ie intake valve or exhaust valve or crankcase/piston.)

With the right tools , the heads don't have to be removed or the engine removed. Just the cam cover, cam, lifters, and lifter carrier..

I prefer to do it with the engine still in the car (just lower the effected side), but a lot of techs prefer to drop the whole engine/trans assembly..
Great info! Thank you for your post!

Do you believe that techs like to remove the assembly in case there may be other issues/damage? Planning ahead?

If the engine does come out, do you recommend any preventative maintenance?

Mike
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Old 07-12-2019, 02:15 AM
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Originally Posted by Rdrcr View Post
Great info! Thank you for your post!

Do you believe that techs like to remove the assembly in case there may be other issues/damage? Planning ahead?

If the engine does come out, do you recommend any preventative maintenance?

Mike
No, I think it boils down to personal preference.

If I were planning to do 1 valve spring, AOS, water pump, coils/plugs on a 996.1 or 986, I would just do it with the engine still in the car, just lowered a bit. To me enough room, is enough room. With the right tools, I can do these with much less work/time than dropping the whole engine/trans unit and THEN STILL having to perform the necessary replacement routines.

Whether the engine is sitting on a lift table or still in the car on a lift , makes little difference to me on those operations. If you add a clutch/flywheel, RMS, IMS, or it's a Tip or a 996.2 AOS, or a 996.2 valve spring, that changes everything !! Then I would prefer to have the engine/trans on the lift table.

All maintenance is preventative maintenance, I think there is no such thing as over maintaining your car. Do as much as your heart/wallet will allow..
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Old 07-12-2019, 11:18 AM
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Sorry, but glad you got it finally figured out and it's fixable.
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Old 07-12-2019, 12:21 PM
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Originally Posted by Porschetech3 View Post
No, I think it boils down to personal preference.

If I were planning to do 1 valve spring, AOS, water pump, coils/plugs on a 996.1 or 986, I would just do it with the engine still in the car, just lowered a bit. To me enough room, is enough room. With the right tools, I can do these with much less work/time than dropping the whole engine/trans unit and THEN STILL having to perform the necessary replacement routines.

Whether the engine is sitting on a lift table or still in the car on a lift , makes little difference to me on those operations. If you add a clutch/flywheel, RMS, IMS, or it's a Tip or a 996.2 AOS, or a 996.2 valve spring, that changes everything !! Then I would prefer to have the engine/trans on the lift table.

All maintenance is preventative maintenance, I think there is no such thing as over maintaining your car. Do as much as your heart/wallet will allow..
As you say, if the engine comes out...and I can afford it, I am considering a new clutch, AOS, RMS and IMS 'solution' installation. But, that'll all depend on the quote.

Are 'newer' 996.2 valve springs any better than the 996.1?

Originally Posted by 808Bill View Post
Sorry, but glad you got it finally figured out and it's fixable.
Me too! Much agreed.

Mike
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Old 07-12-2019, 03:38 PM
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Originally Posted by Rdrcr View Post

Are 'newer' 996.2 valve springs any better than the 996.1?





Mike
No, and they wont fit the 996.1 either. They do occasionally break as well.

The reason I say that the engine is to be removed on the 996.2 is the different cam set-ups, 996.2 has vario-cam plus. The cam timing tools are much larger and you can't use them with the engine still in the car like you can on the 996.1. The large torque-to-angle bolt and the holding tool cannot be used with the engine still in the car..

Like I said 996.1 is much easier and can be done with the engine still in the car, but a lot of techs just pull the engine/trans same as the 996.2, they don't differentiate.
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Old 07-12-2019, 09:12 PM
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^^^^
Gotcha! I'm following you now. Thanks for the additional explanation!

Mike
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Old 07-13-2019, 07:52 PM
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Originally Posted by Rdrcr
Zero compression, cylinder #1.

After checking the engine with a borescope, they believe the intake valve spring for cylinder #1 is broken. The engine will need to be removed to fix the issue. I'm awaiting my quote for the repair on Monday.

The good news...no bore scoring and everything else seems to be in great condition!!!

A broken intake valve spring, or any valve spring in general for these engines seems pretty uncommon.
However, I have read of a couple examples...

I'm assuming the engine does have to be removed to repair a valve spring, correct?
Do the heads need to be removed for this repair?

Any thoughts? Suggestions?

Mike
A broken valve spring is very uncommon, the valve train on this engine is a quite low tention set up, a more common problem is a loose valve seat , probably not allowing the valve to close .
First job would be to just remove the valve cover, you can then check springs but I would bet you might see a valve partially open, this will then require removal of the head to inspect and repair the seat. Hope you get it sorted!
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Old 07-14-2019, 03:50 PM
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Originally Posted by Noz1974 View Post
A broken valve spring is very uncommon, the valve train on this engine is a quite low tention set up, a more common problem is a loose valve seat , probably not allowing the valve to close .
First job would be to just remove the valve cover, you can then check springs but I would bet you might see a valve partially open, this will then require removal of the head to inspect and repair the seat. Hope you get it sorted!
Thank you for your post!

From what I've been told, yes, the valve is partially open.

I'm hoping to get it sorted too!

Mike
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Old 07-18-2019, 01:12 PM
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Okay. Engine is coming out!

My car is a early '99 with a '98 build date.
Should I be considering a LN Engineering IMS retrofit kit bearing for my engine while it's out? I'm also considering a new AOS and clutch while the engine is out.

Thoughts?

Mike
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Old 07-18-2019, 01:59 PM
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Yes, you should!
Do it once and do it right. The IMS Solution is the only one I'd consider. Should you ever sell the car, you will get your money back. Should you keep the car, you'll never have to go back in and do it again.
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Old 07-18-2019, 02:42 PM
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Originally Posted by 808Bill View Post
Yes, you should!
Do it once and do it right. The IMS Solution is the only one I'd consider. Should you ever sell the car, you will get your money back. Should you keep the car, you'll never have to go back in and do it again.
We did discuss installing the solution and I would agree that logically, that's really the only way to go. However, I'm trying to save as much money as possible...I know that doesn't sound wise in this situation but, I hadn't budgeted for this unforeseen engine issue so I have limited funds available. The solution is roughly a $1K more than the retrofit and hours more in labor. I want to do as much as I can while the engine is out, but within reason. I'm figuring that the most important items to address are going to be repairing and replacing the damaged and wearing components of the valvetrain and do as much extra as I can afford while the engine is out.

My goal is to keep the vehicle on the road until I can afford a full rebuild and displacement increase.

Mike
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