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What's everyone's thoughts with the deterioration on my '66 Toronado's exhaust manifolds? Overall it looks to me that they're in pretty poor condition but I find this strange because the car was really well looked after over the years. My Dad has owned it since 1973 and he stored it indoors every winter. 81k on the odometer, never abused. Everything under the hood is in really good condition, however the manifolds have got some really bad pitting all over them. Check out my pics below.
Is this just a case of bad casting or could something else cause this? About the only thing I can think of is that the valve covers were leaking oil for several years......perhaps the oil leaking down and burning on the manifolds contributed to the damage? Much of the damage is in these little round dots of pitting, kinda strange no? I'm not sure what causes these things to go so bad.
I'd say those exhaust manifolds are in decent condition. The only reason you might want to replace them is if you're doing a concours restoration on your car.
I know you can get recast W/Z manifolds from Thornton.Toronado exhaust manifolds would probably have to come from a parts car.
You can have those manifolds bead blasted, then regularly treat them with Calyx exhaust manifold dressing.
I live in NYS STATE, the salt belt capitol of the world. Every 5 to 6 yr old manifold looks just like this if not worse. So from 1966 to 1973 was it driven in the salt ??? You should see what this 2015 ford f-150 looks like that we are working on !!
Last edited by zl1 camaro; Feb 12, 2026 at 07:23 AM.
I'd say those exhaust manifolds are in decent condition. The only reason you might want to replace them is if you're doing a concours restoration on your car.
I know you can get recast W/Z manifolds from Thornton.Toronado exhaust manifolds would probably have to come from a parts car.
You can have those manifolds bead blasted, then regularly treat them with Calyx exhaust manifold dressing.
I wire wheeled and coated them with POR-15 manifold gray high temp. Came out looking better but still looking rough!
I live in NYS STATE, the salt belt capitol of the world. Every 5 to 6 yr old old manifold looks just like this if not worse. So from 1966 to 1973 was it driven in the salt ??? You should see what this 2015 ford f-150 looks like that we are working on !!
No, from 1966 to 1971 it was driven in California. In 1972 the original owner moved from California to Newfoundland, Canada and my Dad bought the car off him the following year. Maybe it spent a winter or two? I don't know if he drove it in the winter before my Dad got it but I can ask. My Dad did not drive it in the winter, stored it every year.
No, from 1966 to 1971 it was driven in California. In 1972 the original owner moved from California to Newfoundland, Canada and my Dad bought the car off him the following year. Maybe it spent a winter or two? I don't know if he drove it in the winter before my Dad got it but I can ask. My Dad did not drive it in the winter, stored it every year.
That is interesting,, that sure does look like salt damage to me.
That is interesting,, that sure does look like salt damage to me.
Oh it just occurred to me that he had an engine fire about 10 years ago. It wasn't catastrophic as he caught it fairly quickly but he used a conventional fire extinguisher to put it out. I don't suppose the extinguishing agent could have done this? I have a picture of what the underhood area looked like not too long after they cleaned it up. I'll post it below:
The pitting looks to be worse on the undersides where road spray (salt) would be more likely than top side. Maybe with the manifolds installed on engine, it's not as much a big deal as when you're getting a full view on the table top. Other than the pits, they do look nice the way you restored them.
All exhaust manifolds were cast iron - along with cylinder blocks, heads and intakes. It's cheap, casts well, machines quickly/easily, etc. However, it also corrodes easily. Doesn't necessarily require road salt. Your manifolds have localized pitting just like most others from that time period. Blocks/heads/intakes typically run at lower temperatures so all the oil that typically leaked from older engines coated them and kept corrosion to a minimum. Obviously, exhaust manifolds run hotter and burn off any 'protective layer'. Leave a cast iron part sitting in a moisture rich environment and it'll corrode - doesn't require road salt - although that will definitely accelerate things.
All exhaust manifolds were cast iron - along with cylinder blocks, heads and intakes. It's cheap, casts well, machines quickly/easily, etc. However, it also corrodes easily. Doesn't necessarily require road salt. Your manifolds have localized pitting just like most others from that time period. Blocks/heads/intakes typically run at lower temperatures so all the oil that typically leaked from older engines coated them and kept corrosion to a minimum. Obviously, exhaust manifolds run hotter and burn off any 'protective layer'. Leave a cast iron part sitting in a moisture rich environment and it'll corrode - doesn't require road salt - although that will definitely accelerate things.
The environment in Newfoundland is pretty salty in general anyway. Usually you're less than an hour from the Atlantic ocean no matter where you find yourself driving so that probably contributes to it. There's certainly no shortage of rain as well and with the car being outside in the summer months maybe it all combined to gang up on the manifolds. I guess it's just the lack of rust everywhere else on this car that has me thrown off.
The car spent the winters stored indoors and in the summer months he'd have it parked in the driveway under one of those fancy fabric car covers when not in use.
Oh it just occurred to me that he had an engine fire about 10 years ago. It wasn't catastrophic as he caught it fairly quickly but he used a conventional fire extinguisher to put it out. I don't suppose the extinguishing agent could have done this?
I bought a CO2 extinguisher for the garage as I never want to experience the clean up after using a dry chemical extinguisher, especially on an engine fire. CO2 leaves no mess, and it can be refilled after use.
It’s got nothing to do with salt . cast iron sweats naturally because it’s a porous metal. when it sits, it naturally absorbs moisture. every time the casting rapidly changes temperature, it burns off the moisture within the surface layer, then reabsorbs moisture in the air as it cools
you see this every time cast iron is rapidly heated, like with a torch,, the area that’s heated instantly shows wetness, especially if the iron is colder
of you live in a high humidity region, it’s worse
Last edited by CANADIANOLDS; Feb 12, 2026 at 05:40 PM.
