free hit
counters
Cats (stutter/misfire) - Turbo studs - Engine/Ancilliaries - The Lotus Forums Jump to content
Grahaml

Cats (stutter/misfire) - Turbo studs

Recommended Posts

Been chasing a stutter/misfire issue on my V8 - I have a suspicion it is cats/exhuast but thought I should check out ignition side first.

Replaced plugs - no difference. replaced coild and leads - again no improvement.

So I turned to the exhuasts and I have found one of the catalytic convertors to be broken up which I think is restricting the exhaust (RH bank).  

I thought initially I would just break them up/remove the innards, However what should have been relatively easy turned out different

Total nightmare getting them off - well rusted and corroded nuts to turbo.  Eventually - with lots of heat/sockets/spanners/vice-grips/files and evential hacksaw got one side off!  Then moving to the left bank - with much better access each of the turbo studs have sheared off.  Well at least the cats are both off now so I will take the guts out to get the car running properly.  

I seem to be giving myself more problems though and I have potentially a big problem with the broken off studs in the LH turbo though - I hope I can get them out - any suggestions?  Access isn't too bad bad on that side for vice-grips and I have a small portable oxy/propane gas kit so I can use that too.  last resort will be to drill ouit as it doesn't look like I can do that with the turbo in place.

I have a MIG welder so even trying to weld on nuts to the proken studs might be an option?

I would rather try in situ as looking at the manual it suggests

"In view of the restricted access and harsh fixings environment, it is generally expedient to remove the power unit from the car before attempting to remove the turbochargers or exhaust manifolds"

I would prefer  to avoid that just for the moment - although if I have to I will....

Then assuming the car is "fixed" I will need to do something about cats befor the MOT (Feb/March I think).  I'm inclined to look at inserting a generic replacement cat into the existing car pipe.

All advice/tips appreciated

Graham

  • Like 1

Share this post


Link to post
Share on other sites
Upgrade today to remove Google ads and support TLF.

Heat and fire are the only ways to undo anything in that area.

anything you replace nut or stud wise - make sure its new !! Don't reuse the old

Share this post


Link to post
Share on other sites

Stainless studs are your friend here if you replace them

Share this post


Link to post
Share on other sites

If repairs are necessary on the studs of the turbine housing, you would be well placed to remove the turbos completely and repair them on the bench.  The ex. manifold to turbine studs are M10, so but better chance of getting the nuts off without those studs snapping.  As Barry already mentioned, you'll need some heat to help get those off.

If you find yourself needing to remove the exhaust manifolds - then I would also recommend to remove the engine from the car.  Although it is technically possible to remove the exhaust manifolds with the engine in-situ, it is only practical when the fixings are in a very good or fresh condition.  In the event that a manifold stud snaps, your will only be able to repair it with the engine out.

In terms of the CATs themselves, I would opt for some 200cpi units.  These will still pass emissions, unlike the 100cpi units.

Share this post


Link to post
Share on other sites

Thanks for advice guys.

I will update you on progress (or lack of!)

Graham

Share this post


Link to post
Share on other sites

i appreciate the studs are f**** hard to remove, and that heat will be needed to help, but I recently used tools like this:

https://www.cromwell.co.uk/shop/hand-tools/stud-extractors-1-2"-sd/661950-4-pce-stud-extractor-set/p/SYK5036950R?utm_campaign=pla+-+&utm_source=google&utm_medium=shopping-pla&utm_keyword=SYK5036950R&istCompanyId=6aa6787b-063e-4414-802d-129f235df603&istItemId=aqrxmwpwa&istBid=tztx

to remove two exhaust studs from a motorbike engine. Better than some methods, at least. There are concentric rollers inside the tool that grip tighter the more you apply pressure. I have to say I have tried all sorts of ways to get studs out in the past-and these were half rusted away-and after soaking in WD40 for two days these came out very easily. I could have used a breaker bar for more torque if needed (although access was perfect for me, and I doubt it will be for you with engine in car).

YMMV of course, and good luck.

 

Edited by LotuStuart
Clarification

Share this post


Link to post
Share on other sites

Well there's not much stud sticking out but acess isn't too bad as these things go.  I cleaned up around the car - thouroughly degreased and wire brushed off as much corrossion as possible around the turbo and especiallty the broken off studs.  I had the car out the garage while cleaning/degreasing and I took the opportunity afterwards while it was out to take it a (short) run - with no exhaust at all - just exiting from the turbos.

That short run rretty much confirmed that the cat(s) were holding the car back - it's nice to have all that power again (thankfully) !!:)

I'm doubtful that there is enough stud showing for the stud removal socket things.  After cleaning I squirted lots of WD then lots of heat from my mini oxy/gas (Oxy-turbo) set I thried with vice grips on one stud.  No luck and as I was applying more heat I ran out of oxygen (little disposable cylinder).  I've ordered some more and  spent a bit nmore time cleaning up around the broken stds and squired some release oil mix and I will leave the studs for a couple of days until the oxygen cylinder arrives.

 

The nuts/studs for the turbo:exhaust manifold looked in good condition: I thought I might try and take the turbo off but although they look good they are bloomin' tight!!!  With lots of leverage I got one to move but it was the whlole stud that actually turned rather than the not on the stud (if you follow!).  I decided I would leave that for now and nipped it up again - I might have to return to them if I need to.

Another thought I had was to pop round to my local garage (family run and usually friendly/helpful) to see if they wouold fancy the job of removing the studs from the turbo.  I figure they will be much more accustomed to this type of problem and they will have "proper" oxy acetylene kit.

 

This is supposed to be the simple bit!!  I still need to cut oped the cats and remove the innards and reweld them.  My welding isn't pretty but I can stick them together - an angle grinder can disguise my efforts.  When it comes to it I think I will try and locate some cat internals - rather than one already built.  If I can get the right size I would fit it into my cats.

Something like the "Mantles" on this site http://www.jetex.co.uk/sports-catalytic-converters/

 

 

 

 

Share this post


Link to post
Share on other sites

I know there's a bend on the pipe - but I'm sure from memory on mine you could see the cat matrix from on end of that pipe.

just smash the inners out with a pipe, rod, stick. 10 minutes and it will bo out and gone - have done it to my old van and one of my old cars years ago.

you can buy sports cats which you just weld in as replacement

Share this post


Link to post
Share on other sites

Thanks Barry,  

That sounds like a better option initially. I would prefer to keep the cats looking standard so when I get replacements that's why I'm thinking I'l cut an opening - a hatch about half way through the cat pipe and lift that "lid" off and insert the cat innards and weld the lid back on.

Interestingly/strangely - the existing cats look different from one another internally - one I can see the cat matrix maybe 3 or 4 inches rom the slencer end of the cat, whereas the other cat I can't see the matrix and poking a long screwdrover down it it more like 10 or 12 inches from the silencer end.  

It will be nice to get to the stage when I can refit them!!!

Share this post


Link to post
Share on other sites

Update:

Cats: I bashed the cores out of the cats - as suggested by Barry - fairly simple.  You may recall I mentioned they looked different inside? The faulty one had the core nearer the end of the cat - past the second O2 sensor - so clearly wrong as the second sensor is supposed to read post car as far as I understand.  There were bits rattling about behing that too - all out now anyway.  The other car had the core nearer the engine - in the narrower part of the cat after the pre cat and before tne post cat sensors - correct I would think.

Turbo: More oxygen arrived today and I also bought a new vice-grip so I had noce sharp teeth to grip the small bits of stud sticking out.  I've also been squiting release oil at the studs over the past couple of days.  However despite heating the area up cherry red and repeated attempts I couldn't get the easiest access one to move and I eventually came to the conclusion that this was not going to happen.  I decided that I would need to taje the turbo off - the studs and studs holding it on looked quite good athough access wasn't brilliant to get the leverage I needed (they were tight!)  However I did manage to get it off and I will tackle the studs with the turbo on the bench tomorrow.  I managed to mange the water return pipe from the turbo - it was siezed onto the metal adaptor into the turbo and the whole pipe twisted.  I just looked and the pipe costs £125 from lotus - I'm sure I can do better than that though - it's a very simple pipe (just looked £112 from JSportscars)!!

My son is an Engineer with a large Engineering concern and offered spark errosion to remove the studs - I wasn't aware of it and have looked it up - might be an eventual option but I will try a few other things first.

This is the end of the turbo in situ showing broken studs 

 

IMG_20170112_151731301.jpg

more pics I couldn't attach above

 

IMG_20170112_151741577.jpg

IMG_20170112_194008655.jpg

IMG_20170112_194018013.jpg

Share this post


Link to post
Share on other sites

What is the condition of the turbo as a unit?  If the turbo is in any way in need of a refresh, you would safe yourself a huge amount of agro by giving it to a turbo refurbishment company.  They will remove those studs professionally and repair/helicoil if required.- plus you will end up with fresh units going forward.

I use Turbo Dynamics in Christchurch and find them to be very honest and reasonably priced.

Share this post


Link to post
Share on other sites

Pirtek will be able to remake that pipe for you. You've a few places up there

Share this post


Link to post
Share on other sites

thanks for the tips - I will look up "Pirtek" to see what options there are.  

Any recommendations for replacement studs and nuts for the various bits?  I was thinking SS as much as possible but read sometinmes that they are either not strong enough or suitable for high temp applications?  I'm inclined to use SS studs and metal locking nuts (K-Nuts or similar).

Mike - the turbo looks OK actually - i just looked through the records I have and I can't see it having been replaced but it was off and on, new oil and coolant pipes, gaskets and studs 9,000 miles ago (although that was 10 years ago).  It looks very good internally so I would prefer to avoid the cost at the moment.  The other turbo looks externally to have much more corrosion around the fittings and when the time comes to take it off it looks like it will be much harder.  

I plan to do the cambelts sometime in the near(ish) future (unless I find someone that can do it for a good/low cost) and so I will probably take the engine out for that.  I will have a look at the other turbo and fittings at that point.  In the meantime I am cleaning up and removing as much of any corrosion anywhere I see it.

Graham

  • Like 1

Share this post


Link to post
Share on other sites

Cosworth have stainless studs on their stuff. You can get them from a few motorsports places.

 

Share this post


Link to post
Share on other sites

Yippee :animier: I bet your pleased about that !!

 

Share this post


Link to post
Share on other sites

Thanks guys - the bolts are in there just to test that everything was OK - I will need to get the studs (SS) now as well as suitable bolts, gaskets and a coolant pipe.

 

Barry - I saw the pipes you (or your garage) had made up -they look great.  Was that Pirtek?  Did you give them the old ones to use as a pattern?  The one I need is bent where it twisted and I eventually had to saw though it so it's not completely ideal as a pattern.  My son has a contact at Pirek through his work so I might see what we can do - if all else fails it's £89+post+VAT to SJ sportscars!!

I'm just listing the studs/nuts I need.  can you guys check I've got this right (or offer advice/alternatives?) 

For the turbo:cat flange

- stainless M8x40mm 

- metal locking - I was thinking copper as it's softer and seems suitable for high heat application - like these COPPER-SELF-LOCKING

The same nuts but M10 (I think - need to check) for the thurbo:exhaust manifold flange - the studs are still OK there.

 

cheers

Graham

Share this post


Link to post
Share on other sites

cant remember if it was 6mm or  8mm or 10mm. But the parts list is correct as is sj site - I remember that much as that's how I bought them via the descriptions on there.

pirtek made the pipe - copied the old ones. I think they put an adjustable split union in somewhere to make future stripping easier. They turn them round really quickly

Share this post


Link to post
Share on other sites

Deroure are great for looking up stuff.

m10 indeed - but not 40mm 

from memory I think I bought 45 or 50mm as they were more available - we just cut them down to size

IMG_0986.PNG

Share this post


Link to post
Share on other sites

Update:

I got a coolant return pipe made up - not an exact pattern buit well made and fits well from an Engineering Company that my son deals with.  Put it all together, filled up the coolant and started it up.  It took a bit more coolant than I expected and took a while to burp all the air out.  Later while looking over the system I found some splits in the overflow pipe to the expansion tank in the RH rear wheel well.  I'm hoping this might explain a slight coolant loss over time I have always experienced.  New pipe now in place.

Anyway - the engine ran pretty rough - sometimes not holding a tickover.  A bit of googling and I suspected perhaps the ECU needed to relearn so I reset it and let it relearn.  Seems OK now - I've had it out probably 30 miles or so since and it's running well - power all restored - perhaps better than before.  Maybe the cats (well one at least) were partially blocking the exhaust - and I suppose the cats would restrict the exhaust in any case?

I was getting an error code from a post cat O2 sensor (P0138)  - that will be the one that I wrecked removing it!!  New one on its way but the car ran well enough regardless.  I also discovered that my dashboard MIL light wasn't working - the bulb was lose - also now fixed!

I will run it a little while like this (MOT due in March) before taking the now empty cats off and inserting a generic 200 cell cat into the existing cat housing.  

I know it's been done before so I would appreciate advice (Gunter?) on the details.

I measured the external size of the are where the cat should go (which is not incidentaly where the faulty one was - it had moved further back - past the post cat O2 sensor!!)

See pictures:

I have a space available of approx 100mm diameter x 85mm to 135mm length.  I'm thinking I take a generic 200 cell cat like in the picture, cut off the conical parts either end and insert it into my cat "chamber" - tack weld it on the outer edges?  I would cut a section out of my cat but keeping it intact so it all fits back on the car and weld the section back on with the generic cat inside.  Not sure if I've explained that well ebnough but any advice welcomed.

Working on the car and waiting for parts has geven me a chance to go over all the rusty suspension - a bit messy!!  I've taken the rear shocks off, removed all the rust with a wire brush on an angle grinder, treated it with a rust convertor as an undercoat the repainted it with hamerite smooth.  Done both rear units and I had an earlier go on one of the fronts in situ but I think I will dismantle them and do them properly.

Ive also discovered what I think is possibly a goot treatment to protect the car underneath.  ACF-50.  I'd never heard of it before - I saw it had been used on some previous work on the car so looked it up.  It's claimed to be aimed at aircraft corrosion protection in hidden areas but it's big in motorcycling circles now too as winter protection.  I've misted it over my repainted shocks and springs as well as all exposed metalwork , threads, nuts and bolts as I come across them.

Maybe you guys already know all about it but if not here's a starter

ACF-50 demo

Graham

cat size.jpg

generic cat.jpg

  • Like 2

Share this post


Link to post
Share on other sites

Hello Graham,

as requested I`m back in the Forum now .. via business PC , don`t tell the Boss :sofa:

 

 

As far as I can recall the small section of the original catalyst can house an 98mm dia aftermarket catalyst, and the bigger section something with 120mm dia.

 

Means, as the Lotus factory catalyst, with all its matching bends and curvature on the pipe, is good for an reuse - just cut precisely only into the weld lines (grind them off).

The sections of the Lotus catalyst are fitted together with an "overlap" style - so you can put them back together after preparation and just weld the "end cap / pipe section" onto it again.

Prior mark the orientation of the pipe section in safe distance to the cut, of Course with some corresponding lines / scratch Points.

 

What I`ve used to pass the German MOT Emission test was just an cheapisch round type 200cell "metal core" aftermarket universal catalyst from eBay  ..

- where I have undone the cones and fitted just the Center sections directly into the original catalyst housing by weld spots, so you need to read the eBay descriptions on dimensions or drawings carefully

The production numbers / verification ID of the original catalyst remained outside, and none could see that inside an aftermarket catalyst (without Registration / type ID) was placed into it.  

Share this post


Link to post
Share on other sites

Thanks for that Gunter - I will try and find something suitable to put into my original (now empty) cat pipes.

Graham

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...