Engine rebuild likely caused by Petrol Wash?

HI Guys,

Just after any thoughts re my 1996 355 spider 2.7 which is just finishing a fairly comprehensive engine rebuild that it shouldn’t have needed. It had a minor service earlier in the year and all was running well, at that time the right hand (by the oil tank) manifold was replaced as it had quickly degraded and holed itself. Joys of Ferrari ownership!. After I got it back it sounded great again and ran very nicely.

I noted at the time they'd over filled it with oil it seemed, never did get round to draining it off but when I checked about 400-500 miles later the oil level was now in-between min-max so thought no probs but kept an eye on it as I have never lost oil before. Over the next 500-600 miles, it kept drinking what seemed to me to be too much oil (0.5-1ltr for 150-300mls) and when downshifting towards a stop/roundabout etc you'd get a slight oil smell. At first I thought the smell due to the service/overfill but then suspected the dreaded valve guide wear. I knew fairly shortly after getting the car back from the service that the other manifold was very slightly starting to go. Ferrari ppi 150 miles ago said possible slight leak on that exhaust (I knew it was knackered), and slightly uneven idle. PPI was as my brother was buying the car off me and I wanted to ensure all was well. In the last 50 miles or so when pulsing the throttle we could get it to smoke a fair bit. Again suspected valve issues but we'd continue to run it as no-one could offer anything more concrete other than possibly v.guide issues. It's done 22000 miles for ref, and only 1 track outing which I think put the nails in the manifolds coffins in hindsight - but it was superbly worth it.

Compression tests reported all around 150-160 dry and cold engine, wet test rising all evenly by about 15-20psi, with one cylinder dry at 130, which basically proves how useless these and leak tests are really in some cases as when the heads came off the guides did indeed have a fair bit of wear, far more than you'd expect but the 130 cylinder had nothing wrong with it. Not to start a separate discussion but read on and you'll see why these tests would not report the truth. So based on everyone saying most likely the guides as all else was ok and no warnings etc the head was taken off for an inspection. The guides were worn, far more than should be acceptable particularly on a 22k car, I've been told by Ferrari and independent alike that between the several hundred uk cars they look after they've only done single hand numbers of valve guides and there is wear but it doesn't seem to cause much of a prob. The problem looked to have been caused by petrol wash on one cylinder (number 7) which under leak and compression checks showed fine as said, for the record my liners were unworn barring 7 and the top end of number 1. Knackered cylinder aside, all rings were less than 20% worn on measurement i.e. 80% of working tolerance left in them, and all parties told me 150-160 were good expected readings for compression so the engine was in very good condition. Obviously except number 7's rings which were mullered and the oil ring had no features on it at all, they were nearly half the thickness of new but still that cylinder looked good on comp and leak tests.

The injectors were all tested as ok before and after a clean. Due to the not so great attention to detail when these were built it appeared a water pipe (I think) had rubbed thru the fuel line vacuum pipe on the left bank where number 7 is and at first we suspected this allied to a duff injector but then as said the injectors later tested ok. Obviously I know the manifold was starting to go, and apparently the throttle bodies were slightly out i.e. one was set to open marginally before the other, poor attention to detail at the last major service I guess but I doubt many if any cars out there are 100% as should be. Also re the manifold, it was going but nothing major and compared the the other manifold which sounded terrible yet no real probs on that bank. So no specific major that would appear to cause a cylinder to start eating itself or is there?

Does anyone have any thoughts over what may have caused this i.e. one or all of - the manifold, vacuum pipe, throttle bodies...HT leads will be tested before they return into the car, new spark plugs (which no-one seems to ever/hardly ever change strangely yet they throw out air filters with 2-3k that you can eat your dinners off!). Have heard of 1 or 2 stories of ecu probs causing perfectly good engines to cause petrol wash etc but not sure if these are myth or reality so just after some advice on mostly likely causes and sensible precautions to ensure the problem doesn't repeat.

Chap I'm using recently purchased a new SD3 but typically they didn't supply him with the manifold test pipe attachments for testing each cylinder, he's going to try to get that sorted etc. but grateful for any thoughts from folks.

cheers

Jon


BIG PS:

For the record can thoroughly recommend the mechanic doing the work, his fixed price servicing is similar to others but includes more such as sd3 diagnostic etc, but other work is only £35+vat per hour which on an engine rebuild makes a huge difference. Full test, strip down, heads rebuilt and guides done, replaced manifold, new big end and main bearings and thrust, polished crank, 2 liners, piston and 2 ring sets, belts, tensioners, oils etc for around £11k. Not nice at all but Ferrari wanted £3k+vat for valve guides, just the guides no labour for head strip etc in there, and £9k+vat for the labour to strip and build engine, so likely would have been around £20k. Not an advert at all as before this saga I genuinely didn't know the guy from Adam, but he's made a very painful situation manageable and the time he's taken over things to get everything right is superb, so more than happy to recommend to other folks as his work deserves a recommendation, I'm sure you'll notice a superb difference in how you and your pride and joy are treated, not to mention your wallet will thank you as well www.grimaldiengineering.co.uk and no he didn’t ask me to put this and doesn’t know I have!

 

I am not a techincal guy but IMHO the only way that this situation coulld have been caused by Petrol wash was if the engine had been running righ and perhaps the whole saga might have something to do with the throttle bodies?

Was a Co2 test conducted?

The fuel line was apparently an issue with some 355's and I remember reading that a recall was instituted but I speak under correction.

 

Hi Jacques,

Not sure re the throttle bodies, likely wouldn't have helped but would have expected more than one cylinder affected, all others on bank are perfect. But definitely not ruling it out, likely though if it was a factor it was one of a few that lead to the end result, or that's the assumption. Unfortunately as originally all roads and thoughts from Ferrari and respected indies pointed to guide issues the head was taken off to check this at which point the bore problem in pot 7 was noticed. Hindsight would have been to check all eventualities but everything did appear fine barring oil consumption, towards the very end some smoke and slight misfire or rough idling, but this was put down as likely due to oil consumption and carbon build up etc.

We're going to look at the opening times and overlay them for the various pots and as said the chaps trying to get the sd3 kit to tap into each exhaust port but as I've learned apparently the computers will compensate quite a bit, so if too much fuel is being dumped in one pot then the lamda just sees that overall and leans the whole bank etc, hence the need to test each pots exhaust. Definitely was curious though if other folks had had or heard of similar experiences or could confirm the ecu's or other things etc sometimes causing these probs.

cheers

Jon

 

Interesting and rather sad story the whole engine business especially as track use was minimal, know our chief Ferrari mechanic down here pretty well, will ask him if he has heard of similar issues..I know a 355 down here thats done about 22 000 km's and of those km's most have been very, verty hard ones and at the moment it seems ok....bar the the rough idle when cold.

 

Ring and cylinder wall wear as you described is not unusual in 355s. I have fixed many. We have been experiencing it since the cars were still in production. The rings wear so bad they are hardly recognizable as rings. It always happens on inner cylinders first (2-3-6-7) because they run so much hotter and for some reason 3+7 seem to lead 6+2 by a pretty good margin.

From running good and no signs of trouble to serious problems takes very few miles and is the reason why I insisit on compression and leak down tests on all 355's in our shop, it is also why I hold them to such strict high numbers on both tests. We also perform leak down tests on every motor we have the heads off after the heads are removed. Many have bad rings and that test will show it.

For what it is worth, by our testing methodolgy I would never refer to a 355 with 160 lbs as good. To me that is circling the drain.

 

Thanks Rifledriver for your input. Wasn't aware of the issues you noted re the central pots etc but makes sense I guess that they'll lead a slightly harder life.

Mine did look more focused though on petrol wash as the piston crown looked noticeably washed (cleaner) on the affected cylinder, others were nice and even coloration, even though pot 7 had been burning copious amounts of oil (unless obviously that would help the cleaning, I'm no expert but assumed that would coke it if anything??).

Good point re the testing of the rings when the heads are off, obviously wasn't too much of a factor as it needed a strip down when we saw the bore anyway and that confirmed the rings were in very good shape on all the other pots barring some wear on no.1 along with the liner on that one, so those were changed as well.

My point re the comp tests was definitely not to offend anyone and not to start a debate on that as I know that can open pandora's box. Obviously will test once things are back together again as that will be an interesting comparison now all the heads etc are perfectly cleaned and fitted, but there seems so much debate on what the correct figures are and then highlighted further by the fact that on pure test results well into the oil ring eating itself local Ferrari garage would have given it a clean bill of health, fairly so I think as I've driven it for 3 yrs and it trully didn't feel or seem different barring the occassional whiff of oil burning and dropping oil levels. Obviously a quick demise changed that.

Concern now is how to ensure this doesn't re-occur and the best checks to make to cover this and safeguard the hard earned dosh that's gone into the rebuild. So any wise thoughts from yourself or other folks on that allied to similar experiences gratefully welcomed.

Thanks for your thoughts, very welcomed

Jon

 

Bad rings will wash a piston dome every time.

Back when I was working in a Ferrari/Alfa dealership on the 2 liter Alfas we never needed a compression gauge we could take out the plugs and just look in the holes with a flashlight. If the piston domes were washed clean we knew it needed rings.

 

The only way you will prevent it in the future is to buy a 360. What you have experienced is a pattern failure of the 355.

 

Brian, is this common on 348's as well or is it exclusive to the 355?

 

355 only

 

Thanks.

 

yeah gee, thanks, looking forward to the future then...not!

if this fails fairly quickly as you mentioned in your earlier post Brian, what would actually initiate the failure after 20K+ miles of no probs motoring?? Is this a case of just slow build up of start-up damage, slow petrol wash etc and then bang it wallops you quickly or is it a culmination of other factors like plug conditions etc??

Jon