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Loc-Nar

Now... Piston advice.

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I was able to remove the engine and have a better look at things. All the pistons have been touched, but only one piston/linder seems to be damaged. JAE says "forged pistons, may be able to re-use", but I am sending these pics so they can have a look, or I may just drive the engine out there so they can check it out. Depending on the diagnosis I can either get one replacement, or just replace them all. If I take the pistons/liners out can I re-assemble without worries as long as I keep them together and in the same orientation, e.g. up-down, 1-2-3-4 back where they came from. Any thoughts? There seems to be no wear lip on the liners at all.

Oh, yeah - Timing belt is missing a slew of teeth.

Steve

BTW, Very impressed with JAE.

post-6115-126748023659_thumb.jpg

post-6115-126748027412_thumb.jpg

Edited by Loc-Nar

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Hi Steven,

You didnt mention in your thread what speed/rpm the engine was doing when the belt stripped the teeth! The engine speed and rpm makes a big difference in the damage caused with piston/valve interferance, I would also be checking the conrods for straightness, and make sure the big ends are not marked on the bearing surface from the impact! Also with regards the cylinder did any of the cam lifters get broken........If so clean everything out as the bits of metal get everywhere!

At this point your in for a complete rebuild which wont be cheap, and personally i would pay the extra and fit pistons as its hard to make sure the impact has not put fine cracks in the piston crowns, Better to replace now them than pull the engine apart a few miles down the road and rebuild it again. Have to agree with you about JAE i have had some parts of them and im from the UK. Get there opion and hope it all works out for you, keep us posted with updates on the rebuild.

Regards danny


A

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I just noticed a loss of power, turned it off, cranked it on the starter and that's when the valve heads broke off in #3. So it was at whatever RPM the starter cranks the engine at. The loss of power happened 1/2 mile from my destination and I was going 30 MPH, low RPM. I have all the build parts sans the piston/liner from JAE. Not terribly expensive, but a little pricey yep.

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One of the pistons needs to be replaced, by the look of it, it was the one to take most of the force and was sacrificed saving the others. They've been touched but I'd guess they're OK. The valves may be different, the touching may have been enough to bend them.

I'd replace the one piston and matched liner if I were you.

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Yeah, all the valves were bent. I have a new full set of rod bearings. I will inspect the mains. I think I cannot remove the pistons because the positions of the rings are impossible to keep in place. Can I just get a new set of rings and hone the liners?

It looks like I can get a set of P/L for around $1000 from UK? I assume there is some huge tax and shipping though. I've been quoted $800 for just one P/L here in the US. Maybe someone has a good one lying around they want to part with :lol:

Edited by Loc-Nar

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You can replace the rings but honing the nikasil liners will be next to impossible unless you can find someone with a diamond hone.

When you get the pistons out and cleaned up, you should find they are each numbered and have a small arrow pointing to the front of the block.


1995 S4s

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I looked into it and a lot of people report to have had luck with using just a ball hone to de-glaze them and prep for new rings x-hatch pattern. Others say the x-hatch will never go away and will wear the rings down. Some say a quick wipe with scotch-brite or no honing at all with new rings. Then there is "only a diamond hone will scratch the Nikasil" and a ball hone is fine.

Here is a more in-depth page that references a nikasil coating place, who I suppose I'll call on this.

http://bmwmotorcycle...o/cylinders.htm

Ah. Here are the nikasil hones, "aluminum oxide", softer material, just to de-glaze:

http://www.enginehones.com/niapho.html

Agh.

Edited by Loc-Nar

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I sent my liners to Lesco somewhere out in California at the suggestion of JAE, they honed them with a diamond hone, however, in order to remove the scratches in my liners, they were then .0075 out of spec so I had them re-nikasilled, which Lesco does also for about $175 per liner, then they rehone them to match the piston specs you give them. If you have the thing apart, I'd just replace it all if you can afford it, worth the aggravation to build it up and never touch it again, in my opinion! I have 4 good stock pistons if you need a piston, pm me if you are interested. I have the rods too! All in good shape, I had a rod bearing wear out and caused a very low oil pressure problem so I rebuilt the thing!

Artie


89 White Esprit SE

...a few little upgrades....

93 RX7.....Silverstone

....slightly modded...Muahaha...

New Addition:

1990 300ZX TT......Hmmm

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With Nikasil there's no real need to hone, the material is so hard it doesn't form the glazed surface iron liners suffer from.

You state you cannot remove the piston because the position of the rings are impossible to keep in place, well to fit rings you have to remove the piston, so just lock the other liners in place (using tools) and remove the one affected liner and piston, then replace with matched pair.

Andy

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Jae reports "leave everything as it is! - replace damaged piston and liner and that's it".

Head may be done on Monday.

I am going to frame the section of timing belt with the missing teeth, the crown of the piston, and the busted off valve heads.

And the recipts.

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I am willing to bet I can just fix this with a file on the lip and use one of Artie's pistons? Thoughts? I suppose the whole thig could be out of round, Maybe send it to Lesco and have them recondition it?

post-6115-126833888037_thumb.jpg

Edited by Loc-Nar

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Ali liner, the coating may well flake away from the area, and creep to an area that is swept by the rings, replace the liner and replace the piston. Used pair will be fine.

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Arnie's original pistons were the non charge cooled type, unless I am mistaken.

Also you do need to make sure they are of the same weight grade (you can mix diameter grades as long as the piston and the liner match eachother, they don't have to match the other 4) or you'll have to balance everything.


Travis

Vulcan Grey 89SE

My Lotus Photo and Projects Album

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If you need a good used set of Grades A SE pistons, I have a set I no longer need, drop me a PM if this is of any interest. No liners though.

Good luck

Malc

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Think about how long it took to get the engine out, the swearing and cussing, getting it all apart all the new gaskets you will need to re-assemble. And then getting it back in the car all the plumbing and wirering and everything else that goes with it. Go on picture it in your mind.

Now ask yourself, "Do I want to risk doing this twice"? :)


Life is like a sewer, what you get out of it, depends on what you put into it. (Tom Leahrer)

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I wonder how I am going to figure out what weight the pistons are, considering I can't see the weight numbers through the carbon. I'll have a go at removing the damaged one this weekend and clean it with a brush, hope it did not get whacked where the # is stamped on it.

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here is what a new piston looks like.

P1010028.JPG

and this is what an original piston looks like (you can barely see the markings)

P5072067.JPG

make sure you clean any bits of metal out of the engine AND the oil coolers!

Edited by Vulcan Grey

Travis

Vulcan Grey 89SE

My Lotus Photo and Projects Album

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Oh! would like to add, for anyone reading in the future, I was really very mistaken about getting a set of the SE pistons for $1000 from anywhere. One NOS piston/liner is a cool grand from Lotus USA per JAE. A set is around 1500 GBP.

I have removed the piston and liner. Easy. Soalking the piston in penetrant to see if I can get the carbon off and read the weight marks. Might try oven cleaner. I've sent Lesco pics and asked if the liner can be re-worked. Even if it is ~$200 to recoat the entire liner I am fine with that. There seems to be a plethora of used stock pistons around but no liners. So if they can restore/recoat/hone it (Andy, I am listening to you about the coating coming off) I will start begging for a piston.

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Ask Mike at Lotus bits or Malc if one of them would ship a liner & piston to you, the chances are they will be in just as good condition as a newly refurbed one as the coating is so hard you can still see the hone marks after 50k, so they get good oil cover and the pistons don't tend to wear.

Andy

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Oh! would like to add, for anyone reading in the future, I was really very mistaken about getting a set of the SE pistons for $1000 from anywhere. One NOS piston/liner is a cool grand from Lotus USA per JAE. A set is around 1500 GBP.

I have removed the piston and liner. Easy. Soalking the piston in penetrant to see if I can get the carbon off and read the weight marks. Might try oven cleaner. I've sent Lesco pics and asked if the liner can be re-worked. Even if it is ~$200 to recoat the entire liner I am fine with that. There seems to be a plethora of used stock pistons around but no liners. So if they can restore/recoat/hone it (Andy, I am listening to you about the coating coming off) I will start begging for a piston.

Be careful degreasing the pistons!

I accidentally stripped the chrom off the tops of my pistons with SimpleGreen and or Gasket Remover (a strong form of oven cleaner).


Travis

Vulcan Grey 89SE

My Lotus Photo and Projects Album

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I just was just cleaning the broken piston. The bore letter and arrow are visible, along with the tiny stamp which must be a serial number and date '0989'? No weight number is visible, but the arrow and the bore letter are not in the place that the service notes say they might be. Are the weight grades stamped on there or just ink as in the one Travis has?

If so I suppose I have to weigh it.

Malc, do you know what bore letter and weight your pistons are? Hopefully the same as mine or heavier smile.gif

I am going to call Lesco, they have not been back to me. If they can fix the liner so they assure me there will be no creeping under the coating and Malc's pistons would fit, or the liner could be made to fit, that might be the way I have to go.

Lotusbits reports they will look around but have none on hand.

Going to check with LotusUSA and see what weight they have for one piston/liner set.

Ah, I talked to Lesco, someone is going to meet me to look at the liner. If they can repair it they suggested a whole JE piston set as another option.

Edited by Loc-Nar

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Steve,

I have a full set of stock pistons that are still good! I replaced mine with the JE set and had Lesco recoat my liners and rehone to match the new pistons. If you are interested in the pistons send me a pm. I have no use for them anymore!

Artie


89 White Esprit SE

...a few little upgrades....

93 RX7.....Silverstone

....slightly modded...Muahaha...

New Addition:

1990 300ZX TT......Hmmm

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Artie,

I thought your pistons were not SE pistons?

I have sent my liners to Lesco, They say the dinged one can be repaired/reocated. I have talked to JAE about the JE pistons to match the liners. If you have SE pistons, what are the chances they will fit inside the liners? There are 2 bore grades, right?

Agh.

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