Ok, so quick update
Ready to replace my 23d because of the leak. Here is a photo of what I ordered. The 123 ignition and it's been mapped by barry spencer as it's the unit he sells. It has a single external o ring. Anyone else running this? Curious if I'll need to beef up or add another o ring around on it.




Sent with Proton Mail secure email.

Steve,
Sorry, I'm a little late to the game, but life has gotten in the way.

The blob of silicone sealant (RTV) in the bottom of the bore in the front of the cam is supposed to be there. Dig it out during servicing, and you'll expose the end of an Allen drive plug that's threaded into/ torque-tightened into a small threaded bore. The front end of the cam has a larger threaded bore for the bolt that retains the cam pulley. Remove that bolt and you'll exposed a glob of silicone sealant... dig it out clean. With the silicone gone, you have exposed an M8 (?) Allen drive plug. Use an Allen wrench to remove the plug.

The camshaft is "gun-drilled" full length... and out the back. At the bak end, there's a thrust washer that is retained by one bolt through it's center and into the cam. The "gun-drilled" bore is tapped at the very back end of receive that bolt and retain the thrust washer. Apply a Thread Sealant to the threads in the bore an on the bolt prior to assembly, then torque-tighten. Allow the sealant 24 hours to cure before attempting to start the engine.

Thread SEALANT is not the same as Threadlocker. Use a Thread "SEALANT"!

At the front of the cam, remove the bolt that retains the cm pulley. Look down into the threaded hole, and you'll see a glob of silicone sealant (RTV) in the bottom of the hole. Dig it out to expose an M8 (?) Allen Drive plug. Use an Allen wrench to remove the plug.

During re-assembly, clean the bore & plug threads to bare metal clean. Then use a Q-Tip to apply Thread "Sealant" to the threads in the bores, and also smear sealant on the bolt's threads & plug's threads. Assemble and torque tighten. Allow the sealant to cure 24 hours before proceeding.

At the back of the cam you're done... no silicone sealant glob required.

At the front of the cam, use Q-Tip or flux brush to coat a glob of silicone sealant over the exposed end of the plug's exposed end, and lightly fill the bottom/ end of the bore in the front of the cam. Allow the silicone sealant to cure for 24 hours.

Now you can proceed with installing the cam pulley, washer and retaining bolt. Apply anti-seize into the pulley's bore and onto the cam's front shank... the bit that slides into the cam's bore. Followed by the washer, bolt and torque-tightening.

At the front of the cam, "IF" pressurized oil gets past the Allend drive plug, and past the glob of silicone sealant, then it's very likely that it will also be able to wick past/ thru the threads of the bolt that retains the cam pulley. "IF" that happens, and oil gets out onto the pulley, there will be a spray of oil flung all across the front of the engine bay, in the plane of the timing belt/ csm pulley. You do NOT want that. She sealed plug and glob of silicone sealant is a "Belt & Suspenders" dual approach to sealing the front of the cam.

*~*~*~*
Oil is pumped up thru the block to the head. It crosses thru the head gasket into a short vertical oil passage in the head... that then stops. Another oil passage is drilled from the front of the head, back until it intersects the short passage. The front of the bore is sealed via an Allen drive plug with Thread Sealant on the threads... no silicone.

From under the head, and oil passage is drilled up, thru the horizontal oil passage, and up toward the top of the head. The bottom of that bore (under the head) is sealed with another Allen drive plug and Thread Sealant... no silicone.

A final oil passage is drilled all the way across the front of the head, starting from the left side, just forward of the exhaust manifold. You'll see a bolt's hex head. On some applications, it's just a bare hex head doing nothing else other than plugging the drilled hole. On other applications, Lotus used that bolt to retain something. In either case, it plugs the drilled hole.

Remove the bolt and you'll see a glob of silicone sealant similar to what's in the front end of the camshafts. Dig out the silicone to expose another Allen drive plug. Remove the plug and clean the threads to bare metal clean.

Assembly is not similar to the cams. Thread Sealant, 24 hour cure, and silicone sealant, 24 hour cure. But now it can (in some applications) be different. There's a washer under the bolt's hex head. Under the washer there "may" be a counterbore with a rubber O-ring inside... surrounding the bolt's shank. One more thing to seal during assembly. Apply a little sealant to the O-ring and in the counterbore, then put it all together. IF your application doesn't have a counterbore under the bolt's washer, don't try to force in an O-ring.

IF that left-side bolt/plug leaks, it can make a heck of a mess down the left side of the engine block. Wind/ slip-stream can also blow any leaking oil back onto the hot exhaust manifold, creating a cloud of oil-stinky smoke. Seal it well,

Again, sorry about the late reply, but there's stuff going on in my life that's causing a distraction. Take it when you can get it.

Regards,
Tim Engel



01/12/2025, 11:41AM, dave78esprit, <armsdc@...> wrote:

The crude clop of RTV is pretty common. There is a grub screw installed with RTV in the front of the cam to seal the opening. The cam shaft is drilled through for oil and then sealed with that screw. You have the rear thrust washer bolt removed how about the actual thrust washer? Is it out or still stuck on the end of the cam? The cam shaft pushes out of the front and the only retention is that thrust washer and bolt. If the washer is sticking to the back of the cam use a longer bolt screwed into the back of the cam through the thrust washer to push the cam shaft forward. The thrust washer will be held back by the housing.

Dave C

01/12/2025, 1:26PM, wigl <wigl@...> wrote:

I am in the process of removing cams from Turbo/HC cam housings and perplexed at why the 1st is stubbornly refusing to budge. The cog wheel and snubber are removed and the thrust plate retaining bolt at the opposite end as well. These components have been out of service for years and the cam does not turn all that freely. No idea what was done in the PO's hands though there's a crude glop of RTV at the forward end of the cam. Insights?

Steve

开云体育

开云体育

The crude clop of RTV is pretty common. There is a grub screw installed with RTV in the front of the cam to seal the opening. The cam shaft is drilled through for oil and then sealed with that screw. ?You have the rear thrust washer bolt removed how about the actual thrust washer? Is it out or still stuck on the end of the cam? The cam shaft pushes out of the front and the only retention is that thrust washer and bolt. If the washer is sticking to the back of the cam use a longer bolt screwed into the back of the cam through the thrust washer to push the cam shaft forward. The thrust washer will be held back by the housing.?

LOTUS 9XX Cylinder Liner Install:

The liner fit into the block's "spigot bores" (the holes in the block that the liners fit into) is very snug. A finger press fit... usually referred to as a "tight" clearance fit. Sit the liner in a starting position on/above the block's spigot bore, wiggle it around, and it just won't go in... frustrating. Then you'll by chance wiggle it into some magic position, and it will almost just drop in. Patience!

With minimal (nil) clearance, don't be painting it with a thick layer of sealant. If you do, all the excess will just get scraped off, and you won't have any control over where the excess mess goes. Apply a minimal thickness "film" of sealant (barely "paint" thick)... NOT a goop layer.

Use a flux brush (for liquid solder flux - cheap & disposable) to "paint on" a THIN/ minimalist layer of sealant.

The liner's outside diameter has a step in it part way down. The smaller bottom end slips into the block's spigot bore... that tight fit I talked about above. Then the liner slips in until the "step" bottoms out against the top of the spigot bore. Paint a thin film of sealant onto the bottom side of the step on the liner, and around the top (facing up) rim of the spigot bore... the two mating surfaces. When those two faces kiss-off, they should be pinching a layer of sealant all the way around.

But not two retched much. Any excess (more than a tiny bit) will ooze out, and end up in the coolant water jacket. You do not want excess sealant to rinse off into the coolant and circulate to where it shouldn't be... wherever that is. Later, just before final assembly, reach down into the cooling water jacket (gap between liner and block's inner wall) with some long slender brush, and wipe off any excess sealant ooze that's on the coolant side of the joint. Be careful NOT to jar/ wiggle/ move the liner... ie, don't disturb it.

Back to applying sealant...
As above, paint sealant onto the bottom side of the liners side-wall step... and for about 1/2"-1" down along the side wall... on the top end of the wall that will slide into the block's spigot bore. A minimalist layer some distance, but short and not all the way to the bottom. Remember the snug fit between the liner and block's spigot bore... a perfect "scraper". Any wretched excess sealant will get scraped up and out the top as the liner's step seats against the block's spigot bore. All that excess will end up around the base of the liner INSIDE the block's coolant jacket. The mess you're supposed to clean-up. How much do you want to deal with?

With the sealant applied, the liner installed, and the excess overflow mess (ideally minimal) cleaned-up, temporarily install the cylinder head. Did you keep the old head gasket? If so, re-install it as a temporary gap filler, install the head, and torque it down to spec. If you do not have the old gasket (or another sacrificial gasket), then tear the cardboard backing off of a couple of paper tablets, cut to fit, and lay them over the tops of the liners before installing the head and torquing it down. Allow the head to sit torqued down for 24 hours or more. Then remove the head and temporary "gasket", clean & prep the surfaces as you would for normal engine assembly, and assemble the engine per the manual.

The exception being the torque spec, which has changed thru time as gaskets changed, and changed with the common use of ARP hardware... which requires it' own, critical torque specs. IF you buy ARP hardware instead of re-using your existing/old LOTUS hardware, it (ARP) requires that you also buy the "current" special thread lube, and then use the unique torque required for that particular thread lube. When you buy ARP hardware from your Lotus supplier, specifically ASK them which lube they will be selling to you with the hardware, and what the torque spec is for use with that lube!!

When it comes time for final assembly, the NEW head gasket only gets used ONCE. Do not install a new gasket as the temporary 'filler' to clamp the liners down while the sealant sets-up, and then think you're going to re-install it during final assembly. NO WAY. A new head gasket only gets used ONCE during final assembly. Any mistake part way thru assembly that requires taking it all apart again and starting over REQUIRES A "NEW" HEAD GASKET. ABSOLUTE GOSPEL !!

Have Fun,
Tim Engel











01/08/2025, 11:30AM PST, Tim Engel, <tsengel@...> wrote:

wigl,
I like Hylomar Universal Blue (the old/vintage spec stuff) and Hylomar AF (the modern/ current version). Neither ever cures hard. It seals very well, but remains softish/ squishie. If it's ever disturbed, it will reseal.

You can use Hylomar Universal/ AF on many things, like the intake manifold, T-stat housing, water pump, gearbox cover... etc. If a roadside repair every requires you to remove the T-stat housing (for instance), and you don't have any sealant along with you, just be careful removing the housing without disturbing the Hylomar any more than necessary. Then carefully re-intall it. The Hylomar residue will re-seal as good as before. I'd still reinstall the t-stat housing with a new gasket and fresh Hylomar when I got home, but for a roadside repair, it's good to go.

What's that got to do with the liners? If you ever have to remove the cylinder head, it is possible/ likely that the cylinder liners might be wiggled a bit... ie, disturbed in their spigot bores. If that happens with Hylomar, don't sweat it. It will re-seal when you re-install the head with a fresh gasket, and torque it down.

The Anaerobic sealants that Lotus specified later (starting with the 918 V8, and retro-spec'd to earlier engines), cure hard/ brittle. IF it is ever disturbed, it will crack, and there is no chance that it will ever re-seal on it's own. It's a great sealant as long as it's left alone, but don't ever mess with it.

IF you do mess with it and damage the seal, your only option is to fully dismantle the joint (ie, take the engine / cylinder block assembly apart) fully clean off any and all sealant residue, and re-seal/ re-assemble from scratch. While anaerobics are excellent sealants, personally, I find that "brittle seal" factor a significant negative.

On the plus side, John Deere tractor dealerships use and sell Hylomar 3400 anaerobic sealant. They have it custom packaged in a smallish plastic squeeze bellows with a plastic 'spout'. Point & squirt. And it's available at John Deere dealerships and some tractor supply outlets all around the country. Otherwise, you can get (well, I've been able to get) Hylomar products at industrial supply outlets, like Graingers... and similar.

Regards,
Tim Engel


01/08/2025, 8:54AM PST, wigl, <wigl@...> wrote:

Which Hylomar?
The original 907 engine called for Hylomar Universal Blue. In modern speak, that would be Hylomar AF.

In later 9XX engines, like the 910 turbo, Hylomar 3400 Anaerobic Sealant was called for.

Are you building stock, or updating?

Regards,
Tim Engel



01/07/2025, 6:37PM PST, wigl wrote: