And with that, I think we've highjacked this thread aplenty I'm not 100% convinced yet that his oil is at fault, although 0w does seem awful thin for these friends. FWIW I run 15w40 conventional because it's dirt cheap.
Thanks for that Steiny, and I have watched this guy's videos before and find him to be very knowledgeable. It's good to hear the scientific basis for what's going on in your engine. But, my profession is science (specifically chemistry), and it sometimes drive my wife crazy!
Well I guess this has turned in to an oil thread. I'll throw in my $0.02 at the end I suppose.
To start though, I pulled the pan and checked out the bearings.
All the other bearings including mains look like they were run on low oil pressure and starved. No blueing or scorching, but heavy uniform wear. The big end of #4 was knocking when the engine was hot and the bearing took a hammering. It was still tight enough that you couldn't feel play by hand. The crank looks like it came out unscathed. It only got 2 second check with a mic but seems fine. All the surfaces look like they did when I got it back from my crankshaft shop. (Speaking of, Yes there are some poorly run shops out there. I went with a shop that's been in business or 3 generations, and has a inscrutable reputation and measured every thing my self again before reinstalling.)
As to the question about the condition of my aux shaft bearings. They are marginal. They took a hit when the aux shaft broke. The tolerance listed in the manual is a mile wide. When installing the replacement shaft it didn't seem too far gone, but I can't think of any way to measure the clearances, and the manual doesn't have a procedure.
So I've ordered new main and rod bearings, and because it was cheap a new OEM oil pump. (If any one wants a 2l oil pump there is a surplus shop on ebay right now with a stock of OEM units for $100 including shipping.)
I installed a Marshall mechanical oil pressure gauge in the engine compartment. I'll need to fab up a hose to relocate it to the dash later.
The plan is to clean every thing up. Install new bearings, plastigage plastigage plastigate and if every thing looks good with the rotating assembly run it and try to kill it again. This time, with oil pressure numbers and I'll run 15w50 mobile 1 race oil.
If my oil pressure sucks, then I will either consider pulling the aux shaft bearings and replacing or may source a second block and build a bottom end up.
Why did I pick 0w40 Mobile 1? Over optimism, and it's cheap (really, $15/gallon from Wallmart, delivered) All my internal clearances were in the middle of the range. My engine startup is very gentile, it gets started, then idled down a long hill and is usually up to temp by the bottom. It spent about the same number of miles with 15W40 cheap oil in it as 0w40 however. So I'm betting I find I am at the low end of the range for oil pressure.
As far as the synthetic vs conventional, I am not going to get in to any arguments on pros or cons, but to my understanding the base oil makes no difference at all, other than in synthetic you can pick the exact size of molecules you want. It's the additive package that matters most (and changing it regularly). I've had this confirmed by friends who worked for Cheveron for years. And as far as the synthetic leaking thing, my experience matches that of Engineering Explained.
Lastly, if I do start a building up a new block, should I stick with a 2L or drop to the 1.8? I've heard some arguments for both. Keep in mind I want some thing reliable to hammer on, and I have to smog so no getting silly.
axelbaker wrote:When installing the replacement shaft it didn't seem too far gone, but I can't think of any way to measure the clearances, and the manual doesn't have a procedure.
Actually looking through my spreadsheet again I have noted dimensions so I guess I did figure out how to measure them. No recolection how I did it. Must have been with a telescopic gauge and a mic.
Front Rear
Bushing ID 1.8932 1.5347
Shaft Journal OD 1.8905 1.533
Clearance 0.0027 0.0017
I'm not a racer nor an engine builder, but your approach sounds reasonable to me. I would suggest replacing the auxiliary shaft bearings based on your experiences. As for oil, I just run 10W-40 as my car is driven mostly in the summer, and it gets pretty hot out here in Livermore.
2.0 or 1.8L? The 2L has about a 1 cm longer stroke, so I have found it to be torque-ier than the other (smaller) blocks. How the engine behaves depends a lot on pistons and cams and such, but as a general rule, the 2L should have more potential for power given the 10% increase in displacement. As for which one is more bulletproof? My guess is that they are similar.
I'll be interested in how this works out, and given your proximity to where I am, perhaps I can see it in action one day.
I'm going to play devil's advocate and say that you are approach is only reasonable IF you can find the definite cause of the destruction. Which I am not 100% convinced you have. Oil viscosity hmm maybe, but I doubt it.
I would make look into rebuilding a different block. They can be had for pretty cheap anyways.
I happened to be looking through some shop manuals, and for what it's worth, the oil pressure spec is around 50 to 70 psi. It varies depending on the particular engine class, but it's generally in that range.
For those with the standard Veglia oil pressure gauge, that's roughly in the mid range of the dial (55 psi is the midpoint mark). My own experience with an engine with some miles on it is around 60-70 psi when the engine is still fairly cold but revved, dropping to 40-50 psi when fully warm and revving. When idling, oil pressure is around 40 psi when cold and 10-20 psi when warm. Again, this is for an older engine that is still in reasonable shape. Going by memory here, but I recall the "low oil pressure" light comes on below 7 psi or so.
Also note that the Fiat oil pressure sending unit can become wildly inaccurate as it ages, usually reading pressures far below what the pressure actually is.
Isn't the thread for the gauge just a regular ol' M10 just like any other car? I would put in a VDO style sender. The ones that have two ports are nice, one for a gauge and one for the idiot light. They can be had for cheap, I think I paid $20 for mine and it is actually really accurate.
I would shy away from running a hose with hot oil in it to the interior. That could become a mess and a half extremely fast.
SteinOnkel wrote:I'm going to play devil's advocate and say that you are approach is only reasonable IF you can find the definite cause of the destruction. Which I am not 100% convinced you have. Oil viscosity hmm maybe, but I doubt it.
I would make look into rebuilding a different block. They can be had for pretty cheap anyways.
As I already own a Fiat, it plays the devils advocate quite well. I am not 100% sure of what killed the motor. At the moment I have to suspect lo oil pressure. If you have a suggestion on a method of finding the cause with out running the motor again I am open. At the moment I have found nothing wrong physically with the motor that explains it. All I can identify is a need for more information. And given a new set of bearings costs less than $100, I see no reason not to destroy a set to learn more.
Yesterday, I started pulling, cleaning, replacing and plastigageing bearings. So far all the tolerances match my notes from assembly. The rods are all measuring 0.0015" clearance. I cannot find any wear on the crank. Ill be attacking the mains today if the rain holds off. The new oil pump will arrive later in the week, though i've had my old one apart and every thing measures to spec.
As to a new block, and that's not happening till spring at earliest. More likely later.
So your plan is to install new bearings and a new oil pump, run a different (perhaps even more correct) viscosity oil, install an oil pressure gauge and run it?
Sounds good to me.
Speaking of which did I order a new oil pump for my current engine rebuild...
Wow, those don't look very good... Especially the #4 connecting rod bearings, which looks like it had galling or something going on where the bearing material was seizing to the surface of the crank. I'm no expert, but it looks like you either had an oil starvation issue, inappropriate bearings, lots of crap floating around in your oil, etc. I think you mentioned that you had an really good machine shop that you used, so you could take the bearings to them and ask them what they think.
+1 to what brian said,
My 0.02$ worth is oil viscosity assuming all the dimensions and clearances were correct on assembly. I really don't like the thin oil that was mentioned earlier in the thread. I would rather see thicker oil.
On question, are all the oil passages in the bearing lining up properly with the crank etc.....silly question i know but hey gotta ask.
do we get to see the crank bearing surfaces too?
cheers
dinghyguy
1981 Red Spider "Redbob"
1972 blue Volvo 1800ES "Bob"
1998 Red Ford Ranger
After building engines over for 30 years (most the size of the average pickup truck) I would say it looks like you had contamination in your oil galley. How did you clean the oil galley in your crank before installing it. Not real sure but when looking through Guy Croft's book I think I saw that they have drive in plugs in the crank galley did you pull and brusk and clean the dead ends for grindings. Just blowing out with air won't get everything out, I have seen bearings look like this from improperly cleaned cranks.
I haven't had a chance to build one of these twin cam yet but can hardly wait looks like you can do a lot with them. Just going to run mine till it starts giving trouble hopefully not to soon.
1978 124 Spyder
1993 XJS Jaguar
Many other over the last 45 years
I'm not 100% convinced yet that his oil is at fault, although 0w does seem awful thin for these friends. FWIW I run 15w40 conventional because it's dirt cheap.
