Heat Exchanger/Radiator Anatomy

[Angela]

Calling all you Detroit breathing/bleeding gurus....

The heat exchanger/radiator "box" on the front of my starboard engine has to come off and get refurbished. A gasket or two started leaking the last time we went out and the whole thing turned to crap quick. There was salt cakes on the floor under it, and now some bolts are very badly rusted as are some hose fittings. Pascal is going to do the muscle work and help me get the beast out. All those nasty bolts are soaking in PB now. There were only about 4 that went bad (rust-wise) all of the sudden.

I'm going to have it dunked at a radiator shop since it's coming apart anyway. Now, speaking of that....do they dunk the entire thing, cast iron box, and all, or just the guts inside of it? I did a pretty good cleaning of this thing fairly recently, and the little tubes inside were so very smooth and clean when I got done...so do I really need to have it dunked?

After I clean up all the rust on it, I'll prime and paint it. Any tips on putting it back together, i.e. do I use any kind of sealant on the gaskets? I've read about some sort of sealant used on the intercooler stuff, but I'd like your advice on what to do here.

On the bottom side of that big cast iron "box", there are two blue aeroquip hoses running to it. What are those? Is there any oil running into this thing and getting cooled, perhaps, or are those water hoses that carry cooling water somewhere to the engine?

Man, this is NOT going to be fun.

Thanks for the help and advice!

[Boatsb]

You are talking about the expansion tank that houses the heat exchanger and the transmission cooler. Get the exploded views before you even start so you can see what is to be removed. there is plenty of opinion on how to clean and repaint it but one thing you need to have is time. It must be primed and painted with a rust resistant paint and allowed to thoroughly dry or it will not hold up for the re installation.

Gaskets and seals and o rings and glands and sealant can all be gotten from the local deteroit parts sources. Use what they or an experianced professional mechanic recommend or there will be leaks. I redid mine and spent the money for the gaskets and sealants ( the good permatex stuff) and had no leaks or weeping.

[rsmith]

If you just cleaned it and its leaking its probably just the gaskets. I replaced all the bolts with ss and replace them everytime I pull the exchangers. Ive found that if you dont use the blue RTV gasketmaker on the gaskets they will wick the salt water and eat the bolts and start that nasty blue green ooze that forms around the edges of the HE end plates. Becareful where you take it I had one f'd up by a guy that tried to weld up a crack and ended up buying a new one. you can do it yourself with a 5 gal bucket and the chemical mix DD recomends. DON'T bend the endplates on the HE I use thin putty knives to work it out. NO screwdrivers.

[Angela]

nasty blue green ooze

BINGO!! I know the gaskets are bad for sure. I've had new ones (from DD) sitting on the boat for a while now trying to get to this, and now, it's at the top of the list. And yes, my leaks are at the gaskets - the one on the inboard side and it appears the one underneath, too. Everywhere salt water touched, rusted badly very fast - as in a day or so. I didn't recognize the problem until I opened the engine room door the next time and my eyes darn near popped out of my head when I saw the transformation.

I do have all of those DD manuals (the whole set) and it does have the exploded views. I'll dig those out in the morning to see what's what. It would be just great if I didn't have to take the "box" off the boat and could just detach everything attached to it and clean it up in place. We'll see. I want to do it right so that the repair is lasting.

[Angela]

You are talking about the expansion tank that houses the heat exchanger and the transmission cooler. Get the exploded views before you even start so you can see what is to be removed. there is plenty of opinion on how to clean and repaint it but one thing you need to have is time. It must be primed and painted with a rust resistant paint and allowed to thoroughly dry or it will not hold up for the re installation.

Gaskets and seals and o rings and glands and sealant can all be gotten from the local deteroit parts sources. Use what they or an experianced professional mechanic recommend or there will be leaks. I redid mine and spent the money for the gaskets and sealants ( the good permatex stuff) and had no leaks or weeping.

That's the thing - the EXPANSION TANK! The transmission cooler is in THERE? Or do some hoses run from there to it? I thought the tranny cooler was down by the tranny side somewhere.

Also, do you have a recommendation the best paint to use for this purpose?

My manuals are up on the truck - it's dark up there - I'll grab them in the morning when I have light and can see them.

[Boatsb]

The transmission cooler is in THERE? Or do some hoses run from there to it? I thought the tranny cooler was down by the tranny side somewhere.

Also, do you have a recommendation the best paint to use for this purpose?

My manuals are up on the truck - it's dark up there - I'll grab them in the morning when I have light and can see them.

Many of the expansion tanks have transmission coolers in the bottom. If it has hoses running to it there is some fluid being cooled in it. Remember we have Oil, transmission and fuel coolers. Follow the hoses and see what it's connected to.

Use the right sealant for each gasket seal based on what it is contact with. There is no "cure all".

Get a hold of a good detroit mechanic for real help. Free advice online is only worth what you pay for it many times.


Paint is subject to argument but I used ACE oul based primer and paint (their version of rustoleoum) and it takes forever to dry. have plenty f time to let it dry thoroughly. This means days.

[rsmith]

When I do mine I go back and retighten the bolts after the first run. Mine is a sandwich of two gaskets and compresses after the first run. The fact that the bolts rusted means the salt got to them. Which it shouldn't if the gaskets are doing their job.

[Angela]

Here's what I'm working with. It's that photo of the underside that shocked me - I cannot believe how FAST that happened.

The other side of that expansion tank doesn't look like that all. I've got "time" for a good paint job - there is nowhere I have to be, and hurricane season is over. I have got to fix this before that engine is fired up again.

[rsmith]

Don't be supprised if some of the bolts snap. its gona be drill and easyout time. I drilled out a lot of mine thats why I went back with ss. I wouldnt try to clean up the hyd hose just get a new one.

[Angela]

I will do all new SS bolts on everything I take off. That's what my yard does with the tranny coupling - they tell me to never re-use old bolts. Is it OK to mix the SS with the cast iron here? I know SS and aluminum tend to weld themselves together over time.

You mention a "sandwich" of gaskets - do you mean just doubling the gaskets? Or is yours different than mine. If it's better to double up the gaskets, I'm going to have to go get some more.

I had no intentions of trying to save that hose fitting! LOL

This is one of those jobs I've never done before, but I am eager to learn - that's how I've tackled stuff in the past. Five years ago, I would have been scared to death to try to do this; today, what the hell....new task! At least those hoses and pipes aren't full of sewage. LOL It seems every Christmas, except for last year, I was elbow-deep in something having to do with toilets and full holding tanks.