S2 Rebuild

[Broadside]

Thought I'd have a look at the engine today, put some oil in, rig up my 'external power supply' and see if I could get some oil pressure. After squirting some ep90 down the very dry suction port in the filter housing and cranking over without plugs the gauge came up nicely (80 psi) great I thought, I'll do a quick compression test (having already noted the valves looking a bit 'brown' through the plug holes) Oh dear, the best cylinder made 100psi, the worst about 25!!
So set back number one, next job is head off, I guess I'll probably drop the sump and get the pistons out while I'm at it in case the the rings are stuck.
Although the guy before me did a lot of work I think it's sat for the best part of 10 years, so who knows what it's like in there!
And there was was me thinking I'll just stick the carb on, rig a fuel header up and try starting it..........

[dakazman]

  Hi Broadside,  " So set back number one, next job is head off, I guess I'll probably drop the sump and get the pistons out while I'm at it in case the the rings are stuck."

  You might would be better off pulling the motor / gearbox as the pistons come out thru the bottom of the liners,  not thru the liners.. unless you want to remove the liners also from the block.

Dakazman

[BDA]

Given the poor numbers you got, you’ll likely have to at least rebuild everything from the pistons up, but a leak down test might point narrow down the area you need take care of.

With 80 psi oil pressure, your bearings seem good and since it wouldn’t make any sense to use new bearings but not replace rings, they are likely in good shape too. So it’s likely that your problem is with the valves. A leak down test would tell you if that’s true or not.

[Sandyman]

Broadside, given that the engine was rebuilt I think following BDA's advice is a great start. Some engines that have sat with some of the valves open may have slight rust on those valve seats causing lower compression. If your plan is to pull the engine anyway, I would first check and adjust the valve clearances, making sure all the valves seat, fire the engine up for a few seconds and recheck the compression. Might save a lot of work.
Sandy

[Broadside]

Yes, agreed, a leak down test would hopefully pinpoint the problem. I'll do that before I get carried away pulling it apart!

[Broadside]

Broadside, given that the engine was rebuilt I think following BDA's advice is a great start. Some engines that have sat with some of the valves open may have slight rust on those valve seats causing lower compression. If your plan is to pull the engine anyway, I would first check and adjust the valve clearances, making sure all the valves seat, fire the engine up for a few seconds and recheck the compression. Might save a lot of work.
Sandy

Yes, I think it may well 'clean up' if I can get it started. I did just back the tappets off to make sure they were'nt holding the valves open. I had to stop after that though as I think my wife thought I was never coming home 

[BDA]

I was originally going to say that if it were me, I'd probably pull the whole engine apart and take a look. I thought that was something only I would do and maybe a bit extreme but Sandyman suggested there could be rust on the valve or seats and that got me to wondering if there might be rust other places. It might still be extreme and overkill but I would probably be more likely to do that now.

[Broadside]

I'd already resigned myself to pulling the head, sump and pistons but didn't realise that the pistons couldn't be removed upwards. Crank out makes it a bit more of a job that I could have done without, that's the joy of a Lotus............

[jbcollier]

Cold compression tests on engines that have sat a long time are never going to be good.  Is it runnable (carb/exhaust/coolant/etc)?  If so, I would try to get it running, decarbonize, adjust the valves and do another compression test on a hot engine.

Don't use gear oil in engines.  Many gear oil have additives that will "stick" to the main and rod bearings and cause a lot of grief.

[dakazman]

  Is this the build your talking about?
   http://www.lotuseuropa.org/LotusForum/index.php?topic=4075.0
 
   Dakazman

[Broadside]

Yes

[Broadside]

Better news today, I thought I'd just see if it would start with a spare DCOE I had in the workshop (of unknown condition and jetting). Rigged a temporary coil up, cleaned and set the points - got a good spark. Fitted the carb, hung a small tank up next to it, pushed the button and off she went! Only ran it for 2 or 3 seconds as no water in it, but it went on all four straight away. Left it a few minutes and tried again, started straight up, again just for a couple of seconds. Next job is get some water in it, service/jet the carb somewhere in the ballpark and warm it up and check the compression again.

[Broadside]

A bit of DCOE therapy this evening 

[Broadside]

Well this week I have taken the body to be final prepped and painted, very exciting!   

[BDA]

That IS exciting!! Please show us some pictures when you get it back! What color are you painting her?