Chassis heat damage caused by Catalytic Converters

[Jim Green]

Just removed the exhausts from the Tuscan to put in a pair of NTEL's Decats, and this is the results of the heat on the chassis from the original cats. I knew what to expect as I'd spent most of the winter underneath the car, and already noticed the damage (Rust)and planned to do it when I fitted the Decats, but it gives owners a clue as to what to expect. This is on a 19,000 mile car, that has never been intentionally taken out in the rain, and not done any track days. So this shouldn't be a bad one. It seems the heat from the cats is so great that it burns off the powdercoating on the chassis which is only an inch from both of the cats.

As oppossed to just putting in the Decats as it was, I spent the day cleaning off all of the rust with a dremmel and flap wheel to get it back to bare metal (Took a while), then I primed it in "CureRust" and masked off the area and gave it two coats of VHT Black. Hopefully after all that, this shouldn't happen again. (Now the cats are gone). Now I know that cats produce alot more heat than a traditional manifold, but you'd think TVR would have taken this into account and fitted some heat resistant sheilding to protect the chassis. So if you have a Tuscan, T350, Sagaris etc, be prepared that yours is probably the same.

I'm glad I got to it at this stage while it was just surface rust.......... Imagine what it could be like in another few years if it had remained untreated. Looks like an area prone to needing replacement in years to come on Speed Six cars if it's not treated early. And it would be an engine out and possibly even a body off job to do it.







And this is on a well cared for car with an otherwise mint chassis

Edited by Jim Green on Thursday 26th March 18:28

[glow worm]

That's pretty alarming Jim...I'll check mine out .
But cyl 6 and the pipes from it are is know for getting extremely hot.

Edited by glow worm on Wednesday 25th March 16:31

[Jim Green]

Alarming : Agreed, be interesting to see how others compare, bearing in mind age & mileage.

[Whitey]

Yep, had mine tidied up and covered with a heat shield when engine was last out. Again that was on a 22000 mile chassis garaged from new and in excellent condition.

Later cars have the silver padded heat shielding fitted all over this area.

[NCE 61]

Whitey said:

Yep, had mine tidied up and covered with a heat shield when engine was last out. Again that was on a 22000 mile chassis garaged from new and in excellent condition.

Later cars have the silver padded heat shielding fitted all over this area.

Some pictures of the heat shielding on this Topic

[Jim Green]

Is this a TVR part, or just someone doing a damned good job of making a decent heat shield..... ????

Edited by Jim Green on Wednesday 25th March 19:04

[T66ORA]

That looks the same as my heat shield on a 2003 Tamora, as Andy(Whitey) has said it was fitted to Speed 6s from around 2002/03 IIRC, i`m sure it can be retro fitted to early cars, ideal while your cats are out.

[VARLEYHYD]

Jim Green said:

Is this a TVR part, or just someone doing a damned good job of making a decent heat shield..... ????

Jim,
Multipart at Crick had these along with the other foil heat blanket sections in stock late last year.
Sorry no part numbers.
Send the photo to Andy at Power and he should be able to track down if still avaiable.

G

[Jim Green]

Many Thanks........ Just dropped Dom an e-mail with the pic.

[Zippee]

Whitey said:

Later cars have the silver padded heat shielding fitted all over this area.

Any idea how late? I've a 54 plate T350 - would this be likely to have the shielding?

[Whitey]

Zippee said:

Whitey said:

Later cars have the silver padded heat shielding fitted all over this area.

Any idea how late? I've a 54 plate T350 - would this be likely to have the shielding?

No, but as you have a T350 you can just open your bonnet and have a look!!

[Daston]

Looks just like mine. 22k miles compelatly covered in rust. All seems surface rust at the moment (I guess its too hot for water to stay about). Any idea on what paint to use? I got some zink undercoat that I am using on the rest of the chassis but I dont think it will stand the heat.

[smithyl23]

My T350c has 57k on the clock and is currently getting a new engine. The rust on the chassis next to cats is horrific (much worse than in the pictures in this thread). If it had gotten any worse, then to fix it the body would have had to have been separated from the chassis.
I'm getting it taken back to bare metal, treated and painted. I'm also getting the waffle type heat shield that was fitted to later models. (Bit pricey though at more than 200 notes). The Heat Shield is shaped and moulded to fit perfectly/flush in/against the chassis.
Glad I caught it when I did. Getting the manifolds ceramic coated as well so hopefully the same issue will not re-appear.

The reason mine was so bad is that one of my exhaust valves had stretched and was not closing properly hence the extreme heat getting through to the manifolds, it also took the cat out due to the extreme heat.

[Jim Green]

Daston said:

Looks just like mine. 22k miles compelatly covered in rust. All seems surface rust at the moment (I guess its too hot for water to stay about). Any idea on what paint to use? I got some zink undercoat that I am using on the rest of the chassis but I dont think it will stand the heat.

The ultimate answer would be "Ditch the cats, and have the manifolds ceramic coated", if you have the time to do it, or the money to get a specialist to do it. But bearing in mind the labour required, (Remove Exhaust manifolds + any anciallries for clearence purposes, remove under trays and exhausts in order to clean the chassis, then take the rusted areas down to bear metal, and treat with something appropriate, sand bast and ceramic coat exhaust manifolds and refit............This could all add up to quite an expensive job).

As an interim job to prevent further damage, and do the work yourself........ the best way I think is to get rid of the cats......this will reduce the temps around the chassis by a significant amount. As for the rusted chassis rails (Normally three of them that suffer the worst, the diagonal, the vertical, and the horizontal chassis tubes closest to the cats....... It's just a matter of spending a day with a dremmel and about six small flap wheels and taking it back to bare metal (Took me all day to make sure I'd got rid of every bit of rust (And I think I've worn out my dremmel.....sounds very noisy now). Then paint it with "CureRust"..... leave it overnight, then first thing in the morning give it another coat.......after lunch get under it with a tin of VHT paint (can states resists 1200 degrees C, and give it two coats. I have some exhaust wrap foil type backed material that I'm going to wrap around the affected chassis rails.......... Thats about as much as you can do.

Have to check how it lasted at the end of the summer.


PS : Sorry for spelling/bad gramar..........I'm rushing ...... Have to pick up girlfiend in a few mins.

Edited by Jim Green on Thursday 26th March 14:02

[Spoonman]

The comments on running without cats seem to make a lot of sense. My Tamora's done 19,000 miles, and for the last couple of years has only had cats at MoT time. The nearby chassis looks a little scorched - but that's all. Nothing remotely like these scary photos.

[Whitey]

Here is a Speed 6 engine showing the hot exhaust.


Here's my before and after photos at last engine whip out time.

[Zippee]

Whitey said:

Here is a Speed 6 engine showing the hot exhaust.

Kineck!!!

[Jim Green]

Yep........ I'd seen those pictures of a Speed Six before, and saw the heat from the manifolds & cats........Note the increased temps as the gasses meet the cats ! ! !

Well, I spent the afternoon checking I'd got all the rusted chassis rails covered in VHT and then started lagging them with manifold lagging. Took a while but it's the best I can come up with at the moment, this should at least protect the part of the chassis that seems to take the most heat. I'll leave this on for the summer and then check them again at the end of the sunny season and see if it's done the job. Hopefully running without cats will reduce the temps as well.







Damned hard to try and keep it looking neat, but at the end of the day it's only me who see's the underside.

The material is supposedly good for resisting heat up to 2000 degrees C.

http://www.agriemach.com/product_info.php?products...

Edited by Jim Green on Thursday 26th March 18:38

[S6 Devil]

Jim Green said:

Yep........ I'd seen those pictures of a Speed Six before, and saw the heat from the manifolds & cats........Note the increased temps as the gasses meet the cats ! ! !

Well, I spent the afternoon checking I'd got all the rusted chassis rails covered in VHT and then started lagging them with manifold lagging. Took a while but it's the best I can come up with at the moment, this should at least protect the part of the chassis that seems to take the most heat. I'll leave this on for the summer and then check them again at the end of the sunny season and see if it's done the job. Hopefully running without cats will reduce the temps as well.







Damned hard to try and keep it looking neat, but at the end of the day it's only me who see's the underside.

The material is supposedly good for resisting heat up to 2000 degrees C.

http://www.agriemach.com/product_info.php?products...

Edited by Jim Green on Thursday 26th March 18:38

How much did you need for this and what have you used to fix it in place?

[Jim Green]

I used about 2 square feet, and it's secured with proper securing wire.

If you bought 1 square yard, you'll have double what you need (Like Me). And the securing wire is stainless steel. (You can just see it in the pics if you look close).