TC engine overhaul

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lindi
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TC engine overhaul

Post by lindi » Fri Oct 26, 2018 11:07 pm

Hello together,

being owner of our lovely '48 TC since two years we are very happy and use it regularly. Last winter a supercharger was added and since then the hill climbing ability has dramatically increased. I played around with the carb needle, as I am used to do it from our other UK-toys and this, together with a slightly increased diameter of the exhaust (recommended by Steve Baker) brought an extra portion of torque, so that performance is really a dream.

Everything could be so fine, if there weren't the excessive oil consumption. Cylinder borings look good (did endoscope them), valve seals fitted, spark plugs ok, only the first shows slight signs of oil fouling, the engine consumes about 2,6 litres every 600 miles. (i.e. 2,6 liter per 1000km, our indication hree in Germany). - Far too much.

So I think of taking the engine out and have a look at piston rings, bearings and these components.

Oil pressure is fine, starting perfect, even from cold, smoke only at idle (but I don't believe such an amount of oil getting passed only through th valve guides ?), but then impressive, when idle duration is longer.

I understand that it is best to pull the engine with the gearbox in situ, what I prefer any way. Is there anything else to have a look at ? Being careful that the gearbox mountings are not twisted, is clear.

As for the camshaft, which I want to inspect at this possibility, what would be the best (not for performance or so, but regarding durability, because we want to run our TC surely more intensive, as soon as the oil problem is fixed)?

I would be very thankful for your tipps

Best regards
Lindi

Tom Lange, MGT Repair
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Re: TC engine overhaul

Post by Tom Lange, MGT Repair » Sat Oct 27, 2018 7:43 am

Lindi - First, be convinced that the engine is burning, rather than leaking, oil. Burning oil usually is caused by one of two problems - worn cylinders and/or bad rings, or worn valve guides and/or bad seals. Worn guides most show themselves when the car has sat overnight, and a puff of smoke comes out when you first start the car; worn bores or bad rings smoke constantly, worse when you accelerate hard (have someone follow you, looking). Worn bearings and rocker bushes/shaft will lead to low oil pressure, not smoking.

It sounds like you have tapered bores and rings that can no longer keep up. A short-term fix is to replace the rings, but it's really not the answer. You need to remove the engine (yes, engine and trans together), disassemble, and have the bores measured by a machinist for taper. If there is a ridge at the top of the cylinder that you can feel with your fingernail, it's a certainty that the bores are worn. You will probably need to have the engine over-bored, get new pistons, and check everything else along the way. With such wear the crank may need to be turned, the cam will probably need replacing, the oil pump and distributor will need rebuilding, etc. This is your chance to do the job correctly, for the longest-lasting engine. There are many cams out there, but the very best camshaft in terms of durability is Len Fanelli's roller cam, where wear is virtually non-existent.

My best recommendation is that you also have the engine balanced. I also sell some good engine parts from which any engine will benefit - see mgtrepair.net.

And don't hesitate to ask questions, as I know you do, and we welcome them!

Tom Lange
MGT Repair

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lindi
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Re: TC engine overhaul

Post by lindi » Sat Oct 27, 2018 8:56 am

Hi Tom,

thank you one more time for your help !

It is ridiculous, when I inspected the cylinders with my endoscope (twice) there were pretty hone patterns to be seen, and of course I looked for indications for ridges, but nothing was to be seen. My wife followed me (and she knows very well what is to look for - not the first time trouble with oil) and she confirmed that under pressure there is no specific increase of suspicious smoke. In the morning no blue cloud comes out. Car starts cold and warm, pulls perfectly and so on. Only thing, as I already wrote, waiting at the red light in idle or in town in stop and go smoke comes out. And then, how I feel, a considerable amount of it.

A short term thing will definitely not be done. In our conditions the TC is THE car to be driven because its quick, small and maneuverable. Our other toys meanwhile by far are not driven so intensively. So not only a few kms will sum up and I am not keen to do this work twice durning my remaining days. Therefore I am interested in a long lasting solution for the well known cam wear problem, too.

You recommend to pull engine and gearbox together. Here in Germany I was told to separate these bits. Just a few minutes ago I have been in my workshop where actually the TC sits on the lift and from underneath had a look at the clearances which are very small at the front end where the traverse for the lamp brackets is situated. Indeed I can not imagine how to pass this with the gearbox in situ.

I will go any way with or without trans, just don't want to be caught by some obstacle while the engine is already hanging on the crane, fingers getting bloody and all such well known cruelities. I think preparation is the most important thing therefore.

One very important aspect you mention is to determine wether the oil is burnt or lost. I think it is so and so. Foolishly I can' quantify the relations. Last season the underbody was not so oily than this year and then the measured oil consumption was about 2 Litres at 1000 km. My opinion, to much, too. But considering relationships would not have changed, then no increase of a damage would have occured.

So, if I would wait on for another season, what would happen? Except of my own personal inconvenience that not everything is perfect on the point, only smoke comes out of the exhaust?

As you see, I am rather unsecure what to do in the moment...

For further improvements I will visite your site this evening. Thanks so far again and

Best regards
Lindi

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Duncan M
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Re: TC engine overhaul

Post by Duncan M » Sat Oct 27, 2018 10:00 am

Synthetic oil always since last overhaul?

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lindi
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Re: TC engine overhaul

Post by lindi » Sat Oct 27, 2018 10:30 am

Hi Duncan,

No, always 20-50 in my period, prior owner, who was a restorer of pre-1905 motocycles, used 15/40. I tried this once with no success.

Cheeers
Lindi

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stephen stierman
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Re: TC engine overhaul

Post by stephen stierman » Sat Oct 27, 2018 6:10 pm

If you don't wish to pull the engine and gearbox, you can remove the engine alone without issue. I have done it a couple of times, preferring to leave the gearbox in the car. Saves removing toe boards and such.

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lindi
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Re: TC engine overhaul

Post by lindi » Sat Oct 27, 2018 10:07 pm

Hi Stephen,

thanks for that !

I read your post here concerning a TB, where you wrote the same.

Please, could you tell me how to manage this in detail ? Especially how to pass the mentioned front traverse with the engine ? Tonight I had the idea to remove the oil pan before, but I am not shure if that's a good idea ?

Of course, this way to do it would reduce required works in a significant extent.

Best regards
Lindi

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stephen stierman
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Re: TC engine overhaul

Post by stephen stierman » Sun Oct 28, 2018 8:25 am

It has been awhile since I pulled the engine last (thankfully), so I may forget some things, but it will come out and go back in this way, believe me. Radiator and shell come out, stay bars, headlamps can stay (cover them up), remove bolts from front motor mts. to chassis. Remove all bolts around bell housing, top and bottom, hoses, wiring etc. Unbolt exhaust manifold from head pipe, or remove carbs and manifold prior. I recall the steering column must be taken loose from chassis mount and the drop arm removed from steering box to get enough movement, I did take the starter out prior to removing the engine. Oil pan cannot be removed with flywheel in place so does not have to come off. The engine will pull forward and than raise enough to allow it to come out over the front cross member. Installation is reverse, make sure to use a clutch alignment tool so the first motion shaft will slide into the clutch disc easily. This often requires some careful alignment of engine when re installing.

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Steve Simmons
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Re: TC engine overhaul

Post by Steve Simmons » Sun Oct 28, 2018 9:15 am

I've pulled the engine both ways also. If you leave the gearbox in place, be sure to support it from underneath. Otherwise the weight will all go to the rear gearbox mounts and the aluminum rear plate can fracture. I removed the starter, carbs, bonnet and radiator, then carefully passed the engine through the headlamps. Placing towels or similar on the headlamps is a good idea. Move slowly and with a helper to avoid banging into the headlamp buckets.
1949 TC8975 / XPAG 9609
1948 TC6011 / XPEG1182 (XPAG6472)
http://www.mgnuts.com

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lindi
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Re: TC engine overhaul

Post by lindi » Sun Oct 28, 2018 11:22 am

well,

a lot of help at a rainy sunday !

I will have to take off a lot of bits, i.e. supercharger, the extractor outlet pipes, modified starter switch and so on.
Taking out the engine without tranny fits me better, anyway.

So far, I decided to check the valve stem clearing om the guides and the condition of the rocker assembly before taking the engine out, because,
- it makes no difference, when it is done
- maybe a light goes on and I find something remarcable for my problem.

The first step in collecting informations is done, thanks a lot !!!!

Best regards
Lindi

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frenchblatter
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Re: TC engine overhaul

Post by frenchblatter » Mon Oct 29, 2018 4:22 am

Wouldn't it be easier to remove the head to inspect the bores and valve guides before taking the engine out.

If you're sure the bores are good and the problem is burning rather than leaking oil then it must be the guides.

Look at my blog and go to "tech index" and select "engine rebuild" http://www.lotus7news.co.uk/MG-TC-HOME.htm

I use mineral 20w/50 oil and, whilst it uses some oil, I don't consider it exsessive (have an oil leak from the front crank rope seal which seals it self then starts leaking, seals it self, star... you get the idea. I may replace it it over winter, see how I feel heath wise.)
Lynne & Norman Verona.

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frenchblatter
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Re: TC engine overhaul

Post by frenchblatter » Mon Oct 29, 2018 4:24 am

Forgot to mention I find it much easier to take the engine out and leave the box in place (suppurted as above). I can probably get a TC engine out in less than an hour and a half now. Probably taken TC engines out in the recent past about 8 times, practice makes perfect.
Lynne & Norman Verona.

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Visit our website to see what this idiot gets up to in his retirement

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lindi
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Re: TC engine overhaul

Post by lindi » Mon Oct 29, 2018 11:42 am

Hi Norman,
very well to hear from you, too. Of course I know your site and love reading it. Story full of life. I confess, I read it with general interest and did not remember all the technical details. Will catch up soon.

But indeed, your suggestion is exactly what I have been again recommended today. I am sure to proceed this way.

Also, I will try to handle with valve sealing, maybe this leads to a improvement, too.

Thanks a lot and the best wishes from cold Bavaria.
Best regards
Lindi

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lindi
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Re: TC engine overhaul

Post by lindi » Fri Nov 30, 2018 9:50 am

Hi everybody,

in spite of my hopings that this autumn should never end, nature turned into white and so there was no escape from beginning, what I announced to do. Preferred the everlasting salt free time, but my prayers were not heared.

What I found when today I removed the first inlet valve springs, was that the modern valve seal, that I installed last summer, has not been anymore in its right place but was moved upwards, so that the valve guide was free. No wonder oil could escape that way very easily, especially because the second inlet valve has the same problem, how I could see through the spring windings. The following two are ok.

So I have to install new seals anyway. They were the usually recommended ones, I will try others --- or go back to the original oil deflectors ?

Valve seat of the one examined valve is ok.

I also removed the tappets and push rods. Rocker arms show signs of wear as does the rocker shaft, which will come new.

Tappets also are worn at their underside, so they will be renewed, too.

At the camshaft only the first lobe shows pitting, another one very very light pitting. All other lobes look really fine. So I am wondering if I could live with it for a while, testing the new sealed valves. If they weren't the reason for the oil consumption, the engine has to come out with no doubt. But perhaps I am lucky ?

Are there any recommendations for tappets, valve seals, and some opinions about the cam ?

And one last thing: This setup with the double springs is really unpleasant to work at. Is there no solution to go with a single spring ?

Thanks for reading and
best regards

Lindi

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Duncan M
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Re: TC engine overhaul

Post by Duncan M » Fri Nov 30, 2018 11:28 am

Due to the low surface area to volume ratio of a tiny o-ring, the original properly assembled valve seal method is not prone to "drying out" from not being in everyday use. The metal deflector and tiny o-ring arrangement works remarkably well under a wide range of engine builds.

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Kenmgtc
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Re: TC engine overhaul

Post by Kenmgtc » Wed Dec 05, 2018 5:50 am

The benefit of leaving the transmission in place is you will not have to remove the prop shaft bolts and nuts which I feel is the most miserable part of removing the engine/trans assembly. Otherwise it is nice to bring them out as a unit, ensuring easy alignment when reassembling, especially if you renew the pilot bushing, plus it’s easy to clean, check and renew any trans items while it’s out (square shift rod bolts, pinned rear flange nut, etc).

Either way you still have to deal with removing the starter and the exhaust manifold/down pipe connection which is the only other unpleasant part of the job.

It sounds like you removed only the head at this point which is the likely source of oil burning given your symptoms.

Good luck!
Ken Klemmer
1948 TC 5510

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lindi
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Re: TC engine overhaul

Post by lindi » Fri Dec 14, 2018 8:07 am

well, some works are done.

All valve guides showed only small clearance to the valve stems, only No.3 outlet was remarcably bigger (0,25mm). There was a very pretty spark plug face, so I decided not to go on in exchanging the valve guides.

All of the o-rings for the outlet valves were very hard. They had been replaced in 1996-1997. Time has been hard to them (as it was to me). One of the valve seals I installed some time ago has been pushed upwards, so the explanation for the spark plug of No.1 being oily and black was found. At least one of the other seals was very loose at the valve stem, so that a sealing function is hardly to be assumed. Also this No.2 spark plug looked not so like I wanted it to have.

The new seals that I bought now are sitting much stronger at the guides and show also a better fit at the stems.
I looked intensively around in the net and found only this one which have the very good fitting measure for the valve guides of our cars. Seem to be a good choice.

Next will be the the rocker assembly. I ordered new parts, especially for interest to see what duration new items can produce versus the old ones. If I will recognize very premature wear, I intend to go for a roller cam. But at first I will try this way.

Wear at the rockershaft is remarcable as it is at the surfaces of the rocker arms where they meet the valve stems. Also new pushrods and followers will come.

I wonder if it is a good idea to go over the top surfaces of the valve stems to make these very smooth. I think of using very fine abrasive paper. What do you think about ?

Best regards
Lindi

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