Seems like something else if you've only got a single valve that is off and there is no side to side movement. Maybe the actual valve stem is worn or there's an issue with the seat? Were the valves replaced when the guides were done? Maybe they missed a bad valve.
Agreed. Just went thru this on my 94 348. Make sure the shop you use tests the spring tension. The WSM has specs. for the amount of tension required for a specific amount of spring compression.
To the best of my knowledge the guides were never done and I have full records of every prior major. So these are 20,100 mile steel guides. My car is well past the assembly number where they supposedly switched to steel guides. I made sure of that before purchasing the car.
If you have high leakdown on one cyl that varies when physically moving a specific valve, it really can't be anything other than a guide/valve/seat issue. I suppose a broken valve spring but I do not think that is likely. I don't think with the valve at max lift it would be particularly easy to feel any play in the valve/guide with all of the spring pressure. Do you have a picture of the leakdown tester? Every dual gauge Matco leakdown tester I've seen, 100psi would be the set pressure. Either way, with what you have found, I would pull the heads and go through them.
Yup What he said. Moving or pushing on a valve during a leak down test and getting a better reading is usually supporting evidence. The guide guides the valve to land on the right part of the seat to seal. Worn guides quit doing that. When you wiggle it around it seals better. Simple as that.
So for a girl's sunny day car at what numbers do you justify pulling the heads apart and replacing steel valve guides or fixing seats, etc? I've seen another thread where someone had leak numbers in the 60's. I'm just over 20% on a single valve. Not trying to blow this off but I guarantee she'll be more worried about what the wind does to her hair than losing a few HP to reduced compression. Do you wait for the next major and see if it gets worse? Do you send it off now and have one or several valve guides inspected and replaced? Do you send it off now and have 40 valve guides replaced, including some (or many) which are presumably within spec?
All up to you I suppose. If you want it to be right it has to be fixed. Otherwise it should run the same as before you removed the engine but you never know how fast it will degrade from this point on. Would it leak down 30 or 40% in a year? As for my particular opinion, I plan to do the guides/valves on mine at the next engine out even if it leaks down perfect. (and would do the same on a 98+ as well). I would prefer it to be 100% rather than marginal.
The major is about half the bill and I think you are already doing one? I doubt it will go to the next without becoming symptomatic. I suspect once the heads are taken apart you will be finding more than one worn guide. I just could not justify not doing all 40 and I would be surprised if there was no need for valves too. I would not even consider taking the heads off without leaking down the cylinders the way shown in Tims photos. It would suck to spend the money just to find out that some of the low cylinders were ring related. One of the things we know about those motors is once the rings start to leak they deteriorate very quickly. Be sure the cylinders alone stay above 5%. 1% is common and 10% is the kiss of death as far as the snowball rolling goes.
I just have no real frame of reference for how bad is bad. Also, with a magnet I'm certain they are steel. Someone asked for pics. Here you go. First is before connected. Second is when connected to #2. Third is after I push the valve with my finger. I had earlier said the leak is halved, but that may have been exaggerated. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Little off topic here Are there any other liner / piston option besides Ferrari OEM that anyone has had luck with?
Honestly don't know. There are others out there. The Mahle stuff is really good and normally last a long time but we know some types of failures on the 355s have caused very rapid and otherwise unusual wear. The problem with Mahle parts as I see it is Ferrari having their usual contract that prevents buying from a source other than the dealer and the prices for a piston/liner/ring set is astronomical. I have not needed to pursue it yet but the Mahle stuff may now be available outside of Ferrari. If so it would be a no brainer.
What did the wear look like on the liner? And how often are Pistons reusable on these things? Thanks 2NA!
i dunno about liners, but for pistons, i am sure JE/ARIAS/WISECO/ and the rest would make whatever you want. I had JE make me custom Honda pistons back in 99. 81.25mm diameter (factory 81), 12:1 compression (factory 9.8 or somthing)
Company and their products changed a lot a few years ago. Know some of what was behind it but probably not really for public consumption.
I have confirmed with Mahle in North Carolina that they are allowed to use ferrari's proprietary drawing. They use 4032 whereas JE has used 2613 which expands a bit more but is stronger.
If Mark decided to put the engine back "as is" what would be the signs of the condition rapidly deteriorating? Would it just be burning oil and black smoke out the exhaust or something else as well? Noticeable power loss and misfiring?
I'm no expect nor will I pretend to be. That being said, the engine is out I would at least correct the one valve . it could be a seating issue from buildup or a bad guide. Hard to tell until its apart. If you don't mind driving the snot out of it, put it back together and try cleaning the valves with hard driving. But you are 85% there if belts are off. Pull the one head .
I didn't think Mahle made the liners?? Their rings they self admittedly get somewhere else not sure where though
