Ali cylinder head repairs

[Chassis 33]

I've got a cylinder head (Toyota 7MGE engine) that has been owned in the past by some heartless bd with no care for using the correct antifreeze in the engine, the result being debris silting up water ways and heavy corrosion to the mating face of the cylinder head on the exhaust port.

Do any folks have experience of welding up ali heads to repair such corrosion, if so who, where etc? Some photos, apologies for the long shadows, I've just taken them!





Regards
Iain

[Justin S]

I've known of Lotus twin cams being majorly welded up to remove cracks in the dishes on the heads. Sadly I don't know who did them. A mate uses a company I believe called motorcast in Wales who overhaul heads he takes off cars and they might be able to help as they repair mashed up heads from broken cambelts etc
here
http://www.motorcast.com/services.htm

[wizzbilly]

i no agra engineiring up scotland used to do a lot of alloy head work not sure if they still do , also worth a try http www.angel-works.co.uk

not used them myself but heard many good storys about there work

[BB-Q]

Is this a rare head (sorry- I'm not too familiar with Toyotas)? If not it's probably going to be cheaper to get another head.

[Boosted LS1]

Most of the corrosion seems to be around the cores so is that an issue, what shape are the gaskets in that area? Do they blank off the cores?

ETA, for cosworths I can have them skimmed or I leave them alone. Usually I leave them alone. The composite gasket still seals them properly. I can weld and skim them but it seems a bit pointless if the surface is flat enough already for the gasket to seal.

Edited by Boosted LS1 on Tuesday 23 June 00:24

[Pumaracing]

I've got 15 years experience of this type of repair and it's not really that difficult as long as the welder knows what he's doing and has the right gear. One job I had to do it on was a historic Daimler Dart 2.5 V8 engine which corrode the waterways in the heads like buggery even when you do use the right antifreeze. Something to do with the high magnesium content in the alloy they cast the heads from. Not a set of heads you want to screw the job up on given how impossible they would be to replace. They were a lot worse than yours but finished up looking like the head was brand new out of the factory by the time they were finished.

The first guy I used for welding many years ago kept sending me jobs back with bits of rock hard tungsten carbide from the TIG torch embedded in the welds. A right sod when you're machining everything back true and the cutter hits one of those, rips it out and shags the job and the cutter at the same time. You have to grind the lot out again, reweld and have another go. Eventually I realised it wasn't just a normal downside of TIG welding like he kept telling me. He actually was just crap at what he did or maybe the equipment was shagged.

The current guy can weld glass to paper as they say in the trade and has a beautiful set of TIG gear. Last job he did that I saw the end results of was to completely rebuild a 4V race engine combustion chamber that had been destroyed by a head coming off a faulty valve at 9000 rpm. Machine out the wrecked seat inserts, weld the whole chamber back up again, grind it to shape by hand, machine out new seat insert bores, fit inserts, cut seats, skim head and Bob's your aunty's husband.

Your job is pretty run of the mill and no real difficulty apart from the waterways are curved not straight which makes milling them back to shape a lot more time consuming. Probably easiest to get them close on the mill and then finish by hand with a die grinder and carbide burr. If you get stuck finding someone local to wherever you are let me know. The old head gasket would be handy to have to see exactly where the waterway shapes match up so don't chuck it out.

One thing I'll just warn you, no matter how good the welder or the welding you'll always get the odd few tiny porosities in the welds caused by blowback from contaminants and crap in the original alloy you're welding to so expect to see a couple of those but it's not an issue. If any appear that are really bad you just have to grind out deeper and weld up again but a good welder wouldn't send a job back with any that would create a problem. The only stuff you can weld to with perfect porosity free results is high quality forged aluminium. All castings have a certain amount of crap in them.

While the head's off it would be the time to get seats recut, valve guides replaced etc if that needs doing. Best go to someone with high end engine experience and equipment rather than just a local alloy welder.

Dave Baker
Puma Race Engines

[Mr2Mike]

The 7MGE was used in the Mk3 Supra wasn't it? Given the pocket money prices you can pick up these cars for I can't imagine repairing that head will be a financially sound idea, unless it's an expensive modified big valve head?

[stifler]

Wot pumaracing said. If you are doing it on a bit more of a budget, PPC magazine did an article about 6 months (?) ago about reviving a corroded head. They took the corroded metal back with a drill bit wire brush thingy. Then they filled it with JB Weld, took it to a machine shop and had it skimmed.


A bit pikey IMO, but if you are on a tight budget, it is a possibility.

[GTMSpyder]

Try Sosbe Welding Engineers in Leicester.....Arthur is an old fella who is an absolute master with any kind of ally weldling with years and years of experience. Last time I was there he had loads of Lotus Twin Cam heads, Fuchs alloy wheels and all kinds of old Brit bike engine and gearbox casings that needed welding. I gave him an Esprit cast alloy rear upright to weld and it came back absolutely perfect.

I don't have his number and he's a bit too old to have a web site but I'm sure you'll get it from Yellow Pages....

[removalizer]

I had a similar problem with a 2.0 ltr alfa Blackpool Road and Rally welded it up for me and did a good job

[HPRulz]

Depends what part of the country you are in, Weldair at stansted airport or Thebus engineering in Bishops stortford did all the weld repairs of casting faults we required on speed six heads and blocks

[Chassis 33]

Thanks for the help folks, I've managed to source a head that was refurbed a couple of hundred miles before the car was scrapped due to terminal tin worm. I'll probably get the existing head repaired over time but there's now no panic.

Regards
Iain

[eliot]

Pumaracing said:

The first guy I used for welding many years ago kept sending me jobs back with bits of rock hard tungsten carbide from the TIG torch embedded in the welds.
Eventually I realised it wasn't just a normal downside of TIG welding like he kept telling me. He actually was just crap at what he did or maybe the equipment was shagged.

Indeed - he probably preparing his tungstens wrong.

My late father did this sort of repair work for over 25 years. Grind or machine it back to get to clean metal as much as possible, heat the head up with a torch, weld it and then remachine / reform the combustion chamber.He used 5 to 10% silicon rods and an ancient 140AMP Miller tig welder - and produced perfect results every time.

From this:
to this:

Edited by eliot on Thursday 2nd July 12:40

[Pumaracing]

That's a superb bit of work Eliot. Your late dad was clearly a true craftsman.

Dave Baker

[DaveL485]

eliot said:

Pumaracing said:

A great post

From this:
to this:

Wow!!! Impressive.

[eliot]

Cheers. He always said as long as the head wasn't cracked and the valve guide hole still existed to pickup the centre of the seat - it could be repaired.

[Chassis 33]

eliot said:

From this:
to this:

Regards
Iain