How often does a 993 typically need a top end rebuild?
#17
Rennlist Member
Maybe you could snake a long boroscope in there? Just a thought.
#18
RL Technical Advisor
Maybe you could snake a long boroscope in there? Just a thought.
#19
Rennlist Member
Thanks Steve. I was just wondering if we could devise a more practical and non-invasive alternative to the wiggle test. The wiggle test seems to be pretty rarely done.
#20
Rennlist Member
I'll be interested to hear what you find out. I know it's in my future. It seems as these things are getting older, it's not a question of if, but a question of when they will need new guides.
#21
RL Technical Advisor
I wish there was one that offered the same qualified results,...
I think the reasons why this isn't done more often is simply due to the time it takes to pull the lower covers and the lack of experience in assessing the degree of movement.
We don't perform PPI's any longer, however when we did do those, that was an integral part of that service so a potential owner knew precisely what the engine needed or not.
#22
Drifting
From what I can tell from years of reading, oil consumption is the only real indicator of wheather or not a top end is need on a '95. Mine has no rebuild, and the oil consumption is minor. I'll pass 160,000 miles next month. It's my daily driver and does track duty several weekends a year.
That is greatness! 160k impressive!
#23
Rennlist Member
How about we see what they look like when they come out?
I've done a dozen or more engines that went close to 200K (granted, 3.0L and smaller, and a major miracle they didn't puke tensioners along the way), and the stem-to-guide clearance is silly. Not to mention intake stem taper itself. Not anything I'd want to subject to track use. But I can do it myself, and I'm funny that way.
The 3.2L I'm putting in "Ruby" (Ed Hughes Targa that I just bought) will get an engine that was done by Bob Grigsby at ~170K original. Came from Hank Watts (Secrets of Solo Racing) '86 cab that was wrecked. That car/engine was bought new, driven into submission at autocross and on track for a dozen years, and held up fine. But it was religiously maintained. So there's the flip side if you want to just keep going and going.
Personally, I've never seen a factory guide on any air cooled that didn't warrant replacement. I've had my hands in 3.6L engines with as little as 20-30K miles that I was in to change rod bolts.
I've done a dozen or more engines that went close to 200K (granted, 3.0L and smaller, and a major miracle they didn't puke tensioners along the way), and the stem-to-guide clearance is silly. Not to mention intake stem taper itself. Not anything I'd want to subject to track use. But I can do it myself, and I'm funny that way.
The 3.2L I'm putting in "Ruby" (Ed Hughes Targa that I just bought) will get an engine that was done by Bob Grigsby at ~170K original. Came from Hank Watts (Secrets of Solo Racing) '86 cab that was wrecked. That car/engine was bought new, driven into submission at autocross and on track for a dozen years, and held up fine. But it was religiously maintained. So there's the flip side if you want to just keep going and going.
Personally, I've never seen a factory guide on any air cooled that didn't warrant replacement. I've had my hands in 3.6L engines with as little as 20-30K miles that I was in to change rod bolts.
#24
Rennlist Member
I'm not one to go off the deep end because I am using an almost immeasurable amount of oil. Its an air-cooled engine, so is my BMW R100 GS and it consumes some oil when filled to the "max" line on the dipstick. The other air/oil cooled motorcycle I have also consumes some oil if filled to the max level...and everyone complains there is a problem, yet they continue making the same mistake...over filling...there is a red dot in the center of the oil level sight glass which is where the oil level should be...not at the top of the oil level sight glass.
As with any wear item, any car make and model included. On my daily driver, I consume zero oil between very long oil change intervals and that is at 135K miles.
#28
Pro
Hi
I had my guides changed at 185k miles. They were worn, the valves themselves were fine. They only got changed because the engine was part for a broken piston ring. We do not have smog tests in the UK though. The engine did not use much oil and never smoked befor the guides were done by the way.
All the best
Berni
I had my guides changed at 185k miles. They were worn, the valves themselves were fine. They only got changed because the engine was part for a broken piston ring. We do not have smog tests in the UK though. The engine did not use much oil and never smoked befor the guides were done by the way.
All the best
Berni
#30
Burning Brakes
This really is a perplexing issue. When I sold my last 993NA it had 53,000 miles IIRC and passed the leakdown with a above 98%. When I had a PPI done on my present tt with only 24,000 miles, one valve guide was badly worn yielding about 70% or so on that cylinder.
The heads went off to Steve and now all is well for many years I'm thinking. The lesson is always have a leakdown performed and keep a cash reserve....Chris
The heads went off to Steve and now all is well for many years I'm thinking. The lesson is always have a leakdown performed and keep a cash reserve....Chris