That sounds similar to every other event of a dropped seat, none of which have been attributed to microwelding after shutdown. I'd be more inclined to believe it if someone could produce a picture of the two components still stuck together.

Again, it being caused by ethanol makes no sense.

 

My wife is pregnant again and my trash cans got knocked over! Goddamn Ethanol!!!!!


Cheers
DD

 

Could be worse. Girl friend is PG!! What will wife say????


So far, my Jeep and Jaguar live OK with E10. My small one bangers
only sorta.


In about 68 or so, my 63 Corvair Camper Van dropped a valve seat.
No noise!!! Just ran on 5 at times and then 6 came in. why mystified me for a time. Then it went on 5 in my drive!!! Pulled the plugs and ran a compression test. Aha, 0 in one hole.


As the Vair had hydraulic lifters, they took up the slack and there was no unusual valve noise denoting the dropping seat;


Why? Heat related, It dumped the belt. An issue of the design with consequences!!!


It's fix is another story.


Carl

 

Yup, I hear ya. Ethanol has been causing humans to do all sorts of dumb things since the Phoenicians started making E5. I know that E40 (usually single malt) still makes me think my lower brain knows best. I'll never learn

 

Well, after spending two days over and under the car I've came to the conclusion this pump is not going to fit without major component changes. Since the car runs within good temp range in all the conditions I through at it, I'll live with that.
Lawrence

 

I yanked the engine-driven pump from my '87 V12 over a year ago and installed an electric water pump. If anything, it has a problem getting up to temperature in the winter (solved by blocking a bit of the radiator with some sheet aluminum panels that keep the airflow down).

I also ditched the engine driven fan and put in a pair of electrics.

In my experience there isn't a problem with the water pump/electric fans running after shutdown. In my installation, the only run for a max of two minutes after shutdown and haven't caused an un-startable condition because of battery drain.

Thanks,

John
1987 XJS V12

 

gotta love those Vairs, imagine if GM had kept building them.

with todays technology of engines i'll bet they would be right up front with the pack.

electronic EFI, todays knowledge of turbo systems, D/I direct injection, belt drive technology(carbon Fiber), and multi-groove belts.

i had a few , best one was a 1965 2nd gen 4 carb Spyder convert.

 

I sincerely doubt we will ever see the valve still stuck to the seat. As soon as the seat is pulled out, the return trip banging it into the head would knock it loose.
If you just type in "valve seat microwelding", you can find a multitude of reading. It does occur. Its one of the main reasons materials that seat are made of has changed so much over the last decade or so.

 

I'm intimately familiar with micro welding having first seen it in the mid '70s when unleaded gasoline was introduced here. It was the removal of lead from gasoline 40 years ago and not blending with ethanol that caused the problem.

Although most car manufacturers had prepared in one way or another for it's introduction, not all motorcycle manufacturers had. My long suffering Norton Commando 750 ate it's own exhaust valve seats in short order.

It's essential to understand that micro welding occurs only under certain conditions- essentially prolonged periods of heavy engine load. A short blast of WOT and high RPM (1/4 mile drag) may raise the exhaust gas temperature to the critical range, but the thermal mass of the head buffers the temperature of the valve seat face sufficiently to keep it out of the danger zone.

If the exposure time to high gas temperature is increased (ex. two up climbing long mountain grades at high speed) then the conditions are right for the exhaust valve face to attempt to weld itself to the valve seat. The size and strength of the weld is not sufficient to cause the two components to remain attached when the valve is commanded open again, but small pieces of material from the seat or the valve face break off and disappear out the exhaust. The result is recession of the valve into the head (reducing valve clearance with solid lifters) and decreased valve sealing due to the rough surfaces.

An old fashioned 'valve job' will restore the sealing properties and clearances, but does not cure the root cause. Some manufacturers resorted to use of valve seat inserts made of hardened materials, while others chose to retain the standard materials but induction hardened the seat area.

The point of all of this is:

1) micro welding has nothing to do with ethanol

2) it only occurs under conditions of prolonged high engine load.

This means that an engine shut down after even the shortest period of idling will have neither a valve face or seat temperature high enough to weld one to another at all, never mind a weld strong enough to pull the seat out of the head during subsequent re-start.

 

You may want to forward that advice to Ford. Appears the new four cylinders of theirs is suffering the same fate as our beloved V12s.
I don't claim to know anything other than what I research for understanding why I have had two valve seat failures. One on my 71 XKE, and the other on my 89 XJS. The XKE had a cracked seat. Never came out completely, but did "****"? in the pocket, and then bending the exhaust valve. My 89 I haven't disassembled, but is making the same noise, and has no compression on 5B, so I feel reasonably assured that it too, is a valve seat problem.
What I found in my research was that the removal of lead was maybe the single most prevalent reason for seat failure. What I also found however, is that ethanol adds a ingredient to the mix that does appear to aggravate the situation of microwelding. I certainly can't argue with the explanation of prolonged engine load. I can only say it wasn't my experience in either situation.
On my XKE, I specifically remember winding it up to about 7K (drag strip idea)? but only for a short burst in second gear, and when I let off, I heard the excessive valve clearance. Compression check indicated a burnt valve, seat, or?
On my 89 XJS, it was a very leisurely drive on a very mild day with my wife. We came home for lunch, and the car sat in the drive for a couple of hours. No excessive load, no driving hard, no remotely running hot, etc. But when I started it, I immediately heard the same noise as my XKE had.
Understandably upset at this point, all I could do was research. At this point, all I can even remotely give credence to is microwelding. When I shut down my engine, my 5B exhaust valve must have stopped (seated), and maybe? microwelding occured, as this is so far, the explanation that seems to be given for the failure of newer aluminum head engines seats.
I am rebuilding a 6.0 right now. I am adding a supercharger. I am also adding Isky cams, electromotive engine management, and a 5 speed. This is a lot of money, time and effort. I don't want to have another valve seat failure. For me, I will be putting a additive in that will replace the loss of lead, just as a precaution.
For most of us, these cars are mostly weekend warriors, toys so to speak. I will justify the addition of a additive as insurance so to speak, and hope it doesn't occur again.

 

Mikey pretty accurate description of the changes of Lead fuel to todays fuels,(petrol).

i owned an engine repair shop for 30yrs, and when that no-lead fuel showed up valve seat problems showed up soon after, most pushrod hydraulic lifter engines had expensive cylinder head repairs. hydraulic lifters would try and take up the slack,so they would also keep running, until lifter ran out of travel, by the time we got hold of those heads would show cracks and powderd metal bits.

the seats had recessed deep into the head(most were hardened cast iron), we did the usual speciality seat installation , regrind or replace valves and seals,gaskets and tune up!

by far the trucks and MOTORHOMES suffered most(hi-load).

 

tr6,, you gotta be a little like me, "Damn the torpedoes, full speed ahead"

all the troubles you had with a V12 , and you aint giving up yet, go for it , probably never have a seat problem again!

 

Not sure if you're referring to microwelding or dropped valve seats. I'd appreciate a link if you've got one.

It still appears that you're connecting the two different phenomena. If you understand that microwelding occurs under conditions of high temperature and load- why wouldn't the valve seats be pulled out of the head at that time?

 

For me, the V12 Jag is the most "affordable"? V12 powered car you can own if that is your thing. I have owned at least 8 V12 powered Jags. I do drive them. And hard at times. I have several cars, enjoy them all for different reasons, but for me, something about a V12 makes me want more, not less, lol

 

yes i'd be interested in that link also,

i'm still in the aluminum heat expanding thing,

i have installed many seats in alloy heads by heating and hammer into head, also have removed seats simply by welding a bead and when cooling they just fall out!

HMM, thats food for thought,
also a cooling system air bubble near a seat could/maybe expand the aluminum also and expand it more than seat, causing seat drop/fallout.

some times refered to as localized hot spots! can cause detonation and a spike in combustion temperatures in that cylinder, increasing aluminum expanding.

in the Jag V12 it still is about keeping the engine cool,!,2 electric fans, an electric cooling pump, and proper maintenence, and an EFFECTIVE air purge system,

 

New tests show Ethanol-based fuel can lead to vehicle damage | Digital Trends

http://www.crcao.org/doingbusiness/R...017March08.pdf

Alternative and Flexible Fuels - AERA

Guys, I think it depends on how much you want to read. These three were from the first page I looked at. The article I can't seem to locate that went into greatest detail was from a engine cylinder head specialist. (I think the business was in Tennessee)
All I know is that for years I've heard about, experienced, dropped valve seats.
I love my V12s, but we have to admit they are a PITA to get out of the car, work on. Time consuming, expensive. Seems there is a lot more to this rather than just running hot. Steam pockets? Additional heat in the V12? One thing I found while reading was that these engines prior to full flow oil cooling generated more retained heat due to the engine oil heating up, and the standard cooling systems only being sufficient when new. Let them become slightly under-maintained, and its like asking for trouble. Seems oil temp can be in the 300 degree range. This heat is transferred to the cooling system. Seems the microwelding occurs at 350 degrees. We know cylinder temps are far more than this, yet after shut down, how far of a stretch of thought does it take to believe that the combination of seat temp, head temp, and the addition of ethenol sets a engine up for premature failure?

 

Your articles refer to damage from E85 and speculates about lesser effect with E20 or E15 in an extremely vague form. No mention is made of any damage from E10. No Jaguars except the most recent models are rated to use anything higher than E10.

Hundreds of millions of cars have driven billions of miles around the globe on E10. No such damage has been reported.

I assume the temperatures you mentioned are degrees F. I can find no reference in any document indicating that microwelding would occur at such a low temperature (350F). Not even tin/lead solder melts properly at such a low temp, never mind valves or valve seats.

 

If it is true that oil temps can get to 300 F on a bypass cooling car, this could well cause all sorts of problems, as even synthetics start to degrade well before that. As far as I can see, the one thing we all lack is actual in-use oil temp figures. I have in stock and ready to fit (not easy as it requires the subframe to be dropped to fit the engine to cooler-flexibles steel pipes) a full flow oil cooling system to replace my OEM bypass oil cooling system. I have also managed to acquire a sump plug with a 1/8 npt central tapping for an oil temp gauge sender. This gauge I shall run off the cigar socket as a temporary item as I do not want to ruin my dashboard or the OEM interior.


Before doing the full flow conversion, once summer arrives, I shall take sump oil temp readings during a long fast run on a hot day, including a couple of heat soak stops etc. If the figures are OK (ie below 100 C, 212 F) I shall not do the conversion! If they are higher, I shall, and will then repeat the test with the full flow cooling system and see what the difference is. If anyone has these figures already, please post then.
Greg

 

these temps below are in F

For a dual-purpose car, engine oil needs to be at least 220 degrees F to burn off all the deposits and accumulated water vapor. For every pound of fuel burned in an engine, the combustion process also generates a pound of water! If engine sump temperatures rarely exceed 212 degrees (water’s boiling point), the water will mix with sulfur (another combustion by-product) and create acids that can eventually damage bearings.
As for ultimate power potential, the general consensus among most racers is that hot oil and cool water make more power in most engines. Cold engine oil causes excessive frictional drag on the bearings and cylinder walls. A quality conventional motor oil will tolerate oil sump temperatures of up to 250 degrees, but starts breaking down over 275 degrees. The traditional approach is to try to hold oil temperatures between 230 and 260 degrees. Even on a short-duration, drag-only combo where oil is frequently changed, I would not want to routinely see under-200-degree oil temps.

shoot for a 240 F with our engines

 

Thanks for this info Jonathan. A bit above water's boiling point is the ideal then; but not too far. 240F is 116 centigrade, so 105 to 115C should be a good general target, do you think?
Greg