Lotus Elan

Markings on my pistons

PostPost by: JonB » Wed May 22, 2019 4:48 pm

Hi

I took a borescope to my cylinders this evening and found some markings on the pistons. A bit vague but one mark is "20" (in Cylinders 1 and 3) and I see "QED" in Cylinder 3 (not surprising as the engine was rebuilt by QED in the 90s).

I don't suppose any conclusions can be drawn from these? 20 thou over bored perhaps? If so would it affect my choice of head gasket?

inkedimg_5518_li.jpg and
"20" (Cyl 1)



inkedimg_5520_li.jpg and
"QED" (Cyl 2)



inkedimg_5521_li.jpg and
"20" (Cyl 3)
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PostPost by: Spyder fan » Wed May 22, 2019 5:21 pm

All the gear and no idea? :mrgreen:

QED make quality items, and the markings are almost certainly +20. Nothing special required for your head gasket, why do you ask, are you contemplating a strip down for some reason?
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PostPost by: Chrispy » Thu May 23, 2019 5:21 am

Make sure your headgasket has a suitable size bore for +20 pistons. I bought a gasket set for my engine and then found out when I got it all apart that I had +40 pistons and the gasket protruded into the cylinder :( Had to order another larger gasket from the other side of the world...
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PostPost by: JonB » Thu May 23, 2019 7:07 am

Spyder fan wrote:All the gear and no idea? :mrgreen:


Hi Alan

The borescope cost something like a tenner off eBay. It connects to a matchbox sized unit that contains a wifi transmitter. Connect your phone to it via wifi, launch the app and you can use the phone as a screen and recorder. Occasionally it is very handy - I've used it to inspect the Aeons and now the pistons. Also came in handy when I was fitting a dishwasher (had to look behind it to see what was obstructing it).

Spyder fan wrote:QED make quality items, and the markings are almost certainly +20. Nothing special required for your head gasket, why do you ask, are you contemplating a strip down for some reason?


I have oil coming out of my timing chest gasket. The head's got to come off to replace the cork gasket, what a silly design. Nothing else is required, apart from removing the broken bolt from the thermostat housing.
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PostPost by: Spyder fan » Thu May 23, 2019 7:42 am

Chrispy wrote:Make sure your headgasket has a suitable size bore for +20 pistons. I bought a gasket set for my engine and then found out when I got it all apart that I had +40 pistons and the gasket protruded into the cylinder :( Had to order another larger gasket from the other side of the world...


Good point if you have a +40 or more overbore, but the standard copper gasket is suitable for +20

https://qedmotorsport.co.uk/qed-shop/lo ... ious-types

Jon,
Are you losing a lot of oil? Whilst I sympathise with those people with incontinent engines I do wonder whether it's worth the effort. While the engine is out make sure you do some other items like the clutch and check all the bearings. The front cover is notorious for weeping oil, don't forget to use a joint sealer.

£10? You were robbed! Just £4.72 here https://www.ebay.co.uk/itm/Waterproof-7 ... SwpkJc0kSR
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PostPost by: JonB » Thu May 23, 2019 8:02 am

Actually it was £18.88 but I bought it in 2017 and naturally did price comparisons - it was one of the cheapest at the time.

Looks to be something like 20-30 ml of oil left on the garage floor after a run - who knows how much is dripping out as I drive? It's enough to be of concern to me, but I also have a new clutch to fit and I want to do some gear shift improvements. So, "engine & box out". I've got a new dashboard as well. I think pulling the engine will make it easier to get the ambient temperature bulb and tube out. Finally, the engine bay needs a general tidy and there is some work to do in the nose cone (relocate the headlight relays I fitted, make improvements to the headlight pod pivots).
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PostPost by: richardcox_lotus » Thu May 23, 2019 5:57 pm

Mine has started leaking from there as well, just keep an eye on levels - it’s helping to keep rust off bits and pieces.

A rebuild at present is a step too far for me.
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PostPost by: JonB » Fri May 24, 2019 7:39 am

Hi Richard

It's not a rebuild I'm planning, just take the head off and renew the gasket seal. I have some repair work to do to the head but that's all. It's a very healthy engine with just a small puff of smoke on the overrun (according to Spydercars but I haven't noticed anything myself) - this would be slightly worn valve guides. I could do this without taking he engine out but as you can see from my earlier posts, I have some other stuff to do as well, so it makes sense to me to pull it.

Problem is going to be resisting the "while I'm there" syndrome!
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PostPost by: Chrispy » Sat May 25, 2019 12:57 am

I think that pulling the engine over just the head is well worth the little bit of extra time. Especially if you have some other leaks and whatnot to fix. So much easier working on an engine on the stand - save the old back!
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