Exhaust Manifold Replacement - Esprit Turbo

[Esprit2]

Dr.Hess said:

In the "Expansion valve help" thread, Dr. Hess asked… Not to change the subject, but ball-park, how long does it take to pull an exhaust manifold in-situ? 89 non-SE. Any tricks?

Dr. Hess,

I've taken the liberty of starting a different thread since this is a ways off the A/C subject. ;-)

The last manifold job went without a hitch with no unplanned side-trips. It took about about 3 hours start to finish.

However, getting the turbo-related nuts-n-bolts off can be time consuming if they're stubborn, and they usually are. If you snap off a bolt or stud, the time to fix that will add significantly. If the broken bit is in the old manifold, that's not a big deal, but there are still enough other fasteners to be a problem. The studs on the turbo that mount the exhaust pipe are prone to snapping as the nuts are removed. Take it easy.

Start by soaking the turbo fasteners with penetrating oil for a day prior to starting. Apply frequently and let them soak.

Access to the turbo mounting bolts is poor. I like to remove the boot floor/ bulkhead first. It takes time, but the improved access makes access to the turbo bolts so much easier that it's faster in the long run.

The best method I've found for getting on the turbo bolts is to use a socket with an integral U-joint. A separate socket and U-joint combined is too long to fit in the available space, but the integral unit fits. It's worth the investment. John at WC Engineering swears the Snap-On version is the only way to go because the fit on the hex-head is excellent… minimal chance of rounding off the hex. However, I've had no problem with the fit of the Craftsman version, and the socket portion is not as tall… it fits into the available space better. Anyway, that and a couple of long extensions will get your hands back where you can get a better grip and apply more force.

Easy on the force. Those bolts have been through heat-hell and are brittle. And they're usually stuck. Bring the torque up on the paranoid scale. If they don't pop loose with reasonable abuse, apply more penetrating oil. When they do pop, don't try to just spin them out all at once. They're rusted in and will fight tooth and nail all the way out. If you just keep cranking on them, sometimes they'll snap halfway out… about when you think you're home free.

When it pops loose, apply more penetrating oil and work the bolt back and forth. Now the oil has a gap to flow into… help it along. Back the bolt out. If it hits a hard spot, don't force it more than a turn or two. Then screw it back in and out a gain… plus another turn. Then in and out plus another.


The manifold itself it just a matter of poor access. It's not technically challenging, it's just a test of flexibility. Small arms & hands combined with multiple wrists and double-jointed fingers helps.

Support the engine and remove the left engine mount strut/ leg. The large vertical bolt in the outer end of the strut is too long to remove… it hits the bottom of the manifold. But you can at least loosen it, unbolt the inner end from the block, then swing the strut out of the way.

A few of the nuts can be reached with a small socket on an extension. A ¼ inch drive works well since the bits are all generally smaller and the extensions are so slender. But most of the nuts will be one flat at a time with an open end wrench. Collect all the short open ends you can get your hands on, all with different angles between the head and handle. Smaller, thinner heads are good as are shorty wrenches. Then it's just patience. One nut I had to use three wrenches, one flat at a time, switching wrenches between flats. Patience.

One of the nuts on the bottom, toward the front is in a notch relief cut into the manifold. 3rd stud? Look for it. The relief isn't cut deep enough for the nut to spin off the end of the stud. It hits the end of the relief long before coming off. So all the rest of the nuts must be backed off far enough to allow the manifold to be pulled back far enough to continue turning that one troublesome nut. It's a three handed job.

Absolutely do not forget about that PIA nut when installing the manifold. It has to be installed before any other nuts are run all the way home. Hold the manifold away from the head so you can install the one nut and then proceed with the others. If you cinch the manifold down with other nuts before installing that one, it will not go on. No way.

If you completely remove the motor mount strut after the manifold comes off, be sure to start the long vertical bolt through the rubber mount before bolting the new manifold in place. That big bolt will not go in after the manifold is in place.

The OEM manifold-to-head gaskets are double laminate stainless steel. A friend used to get triple laminate gaskets out of England for me that were better. I never knew if they were Lotus-UK OEM or aftermarket, but LCU didn't have them. I sent some samples to Jeff at JAE, and he now sells a different version of a 3-lam gasket. I don't know how widely available they are now, but JAE has them and they're worth the trouble to locate.

Use stainless studs if you have to replace any. Use the special small-hex, copperized, distorted-thread lock nuts available from Lotus parts suppliers. It's best to use all new nuts on assembly.

When you re-install the motor mount strut, use medium strength Loctite on the threads (blue, 243 / 243). The bolt holes in the block are drilled and tapped deeper than the OEM bolts reach. I measure the depth and then put in the longest bolts that will fit… grab all the thread you can. Last time I also used Allen drive cap screws on (?) two of the locations. It's easier to get on them with about a 6" long, ball-end, Allen wrench with socket drive (ratchet). The third bolt (bottom front?) is tucked in behind the strut leg enough that there's really no choice other than approaching it from the side with an open end wrench.

It's a nasty job at best, and it can go rapidly down hill from there. Good luck.

Regards,
Tim Engel
Lotus Owners Oftha North

[Dr.Hess]

Thanks, Tim. Looks to be a typical Lotus job. I am afraid it is getting that time for me. 53K miles and there are some cracks. One big one behind #4 runner. Nothing leaking yet and I don't want to do this until after the British Car Show here in about 5 weeks. After that, I'll dig into it and probably just make me a new one from some 304 stainless, or try my hand at welding up the original one or both. I think I can make one from .120 wall 304 that should be plenty strong and not have to worry about the turbo hanging off 16 ga tubing. It should be no problem duplicating the "just make it fit and damn the runner lenghts" original manifold. That thing must be one step up from a log type, efficiency wise.

Dr.Hess
Lotus Owner of NorthWest Arkansas (LOONWA)

[Del-Esprit]

Just finished a Manifold replacement myself and can vouch for what Tim has said about being patient with the bolts and it being a three hand job at times.

Replaced the manifold with engine in place, found jacking side up left side to cant engine over a little gave a better access to top bolts. Remember to undo gearbox mounts if you do this.
Rather than use lots of openend spanners, I found an old ring spanner and dremeled down on side of ring so that it fitted between not and manifold.

Give yourself as much space and access as possible, so remove boot floor pan and anything that can reasonably be removed.

This is relevant to my S4s not sure how different it will be on yours.

Del
95 S4s


>> Edited by Del-Esprit on Tuesday 31st August 22:16

[Dr.Hess]

Thanks Del. I have a collection of custom Lotus tools such as you describe. One of my favorites is the 13mm combination wrench bent into a 3D S that is perfect for one bolt on the shifter, the left front. Another is the combination wrench box end ground down to half thickness so it will fit over the timing belt tensioner and hold it while you tighten it with the other wrench. I first go through my box labled "Junk Tools," then down to the pawn shop to look through their junk for the tool to customize. Last trip came up with a large open end wrench to get the angle treatment so I could tighten the oil pressure gizmo on the wife's Sportster without taking half the bike apart. U$0.25 plus a few cents acetyline gas and O2.

Dr.Hess
LOONWA

[Esprit2]

Dr.Hess said:

(Snip)... After that, I'll dig into it and probably just make me a new one from some 304 stainless, or try my hand at welding up the original one or both. I think I can make one from .120 wall 304 that should be plenty strong and not have to worry about the turbo hanging off 16 ga tubing. It should be no problem duplicating the "just make it fit and damn the runner lenghts" original manifold. That thing must be one step up from a log type, efficiency wise.

Dr Hess,

Making tubular turbo headers is problematic since they tend to crack. Talk to (??) Marcus. I think he's had a stainless tubular manifold for the Esprit Turbo for quite some time. It's mentioned, but not yet for sale since the cracking bugs haven't been worked out yet. And it's been years.

On turbo engines, there's more to be gained by short direct runners that deliver the hottest gasses to the turbo than there is by tuning the header for optimal scavenging. And the thick cast iron walls help keep the exhaust gas hot too.

Installing a tuned length, tubular header between the engine and turbo would cool the gases, resulting in more power loss than could be gained back with improved scavenging.

For what it is (short and direct), the Lotus cast iron manifold flows very well. There's not much to be gained using tubes. Unless you can figure out the cracking issue.

Regards,
Tim Engel
Lotus Owners Oftha North
Minnesota, USA

>> Edited by Esprit2 on Wednesday 1st September 07:47

>> Edited by Esprit2 on Wednesday 1st September 07:51

[Dr.Hess]

Hey Tim,
Well, I think I will address the cracking issue by doing like my civil engineer friend who designed several of the 610 bridges in Houston did: "Make it real stout and figger it 'oughta hold." Normally, tubular headers are made from 16 ga mild steel, and I plan on using 120 wall 304 which is about twice as thick, roughly and handles high heat better. I was planning on 3/8" for the flange, but I may up that to 1/2" given the cracking issues involved. Anyway, I think it is worth a shot. Making headers is very labor intensive but not too expensive materials wise. I would guestimate around two to three bills materials and plasma/water jet fees plus subbing out the final welding to a TIG expert who can do about 100 times better than me and my MIG, although with these thicknesses involved, I could probably go SMAW and not have to worry about burning through. Still, the professional TIG welds just look so much better, it is well worth the $35 they would charge me.

It took me about 6 weeks of all my spare time to make the header on my Seven, but I think this one will not be as bad as I am now up on the learning curve. I have the CAD software, etc.

Dr.Hess

[rlearp]

We used to use tubular headers on SVO Mustangs (turbo four banger) and the results were no different than using a hogged out stock E6 casting iron manifold.

However, they can be made to work just fine. Weld gussets from 1/8" or 1/4" steel in at critical locations to bear the weight and it won't be a problem. Wrap them too, because as pointed out you want the heat and the cast iron manifold does a good job of getting the heat to the turbine.

One thing I remember about the SVO was that it had a brace that took the weight of the turbo in the form of a rod that connected the turbo to the side of the block. I wish Lotus had done something that intelligent instead of perching the 15 lb turbo way high on the end of a long manifold with no other support.

Since my stock manifold has numerous welds now from cracking if someone came up with a tublar header that would hold I'd get one as a replacement and retire my stock one.

R

>> Edited by rlearp on Thursday 2nd September 15:59