Heat Exchanger/Radiator Anatomy

[dsharp]

I Imagine he's talking about there being 2 gaskets on the end with the tube bundle flange. One gasket under the flange then the gasket over the flange then the end piece. Is the main housing cast iron or cast aluminum? Like you noted stainless and aluminum don't mix and it's hell to drill out and not take off through the aluminum. I used permatex 2 in the tube. It's not rtv but, it's about the same thickness.

[dsharp]

It would help to change out the zinc pencils every season. Get a few good drill bits and eze outs unless you're extremely lucky.

[Avenger]

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.

Oil-based paint is definitely the way to go for this. I had the same problems with the stuff taking forever to dry. Tried using heat, and it would make the paint wrinkle. Then somebody suggested "Japan Dryer." It acts as a catalyst to make the paint kick off and usually has it dry enough to handle in less than a day. Should be available in paint or hardware stores. It only takes about a thimble-full for a job like that.

Re: the bolts. There's a number of approaches. Certainly try soaking them as much as possible. MikeP always recommends applying tightening before trying to loosen. I've had limited success with that on rusted-in stuff, but it's worth a try. Then there's shock. A good, hard hammer hit with a brass punch (so you don't mush the bolt head) sometimes helps to jar them loose. Next up, heat. The old Bernz-O-Matic is worth a try. Heat where the bolt threads in, not the bolt head. Usually more heat is required which is where the oxy-acetylene comes in handy, if you have it handy. If you can get the bolts to start moving but they tighten up when you start backing them out don't apply more force. You'll need to soak them more and try to work them in and out hopefully getting them further out each time. Patience is mandatory.

Dealing with broken bolts is a whole 'nuther (sorry SKY) paragraph and a half so let's jump off that bridge only if we get to it.

Can you tell I've dealt with a lot of frozen hardware before?

Good luck!

[Boatsb]

Do you have a way to add the japan drier to the spray cans?

I bought a small can of paint to touch up and the drier is a good idea. I know flow enhancers wont help but that could be the answer where I brush on the paint.

[Avenger]

Never had a problem with the spray cans drying. I use the dryer when I'm mixing for the spray gun or brushing.

One thing I've noticed about the oil-based is that it tends to skin over which prevents the bottom layers from drying so I try to wait a while between coats to let it start to set up.

[GJH]

Those lines underneath, BTW are the transmission oil cooler lines; follow them and you will see one goes to the trans oil filter and one from the trans housing. The trans oil cooler lies within your tank.

Looks like the last re-install of the heat exchanger was botched. It pays to follow the shop manual instructions very closely. and have a pro do it the first time and watch carefully. As for the SS bolts, Tef Gel is excellent for un-like metals.

[Bill Allen]

Yesterday I finished cleanning the heat exchangers on my 6-71's. Wound up with a weeping gasket turning into a leaking gasket. It was the side outlet foe the raw water. The housing that the gasket sealed was bronze or red brass. Held on with four bolts which were stainless steel. Looked really bad when I took it off salt build up from weeping and paint peeling. I keep good gasket material in my spare parts, so I cut a new gasket and cleaned everything up. Put it back togther with the old ss bolts. Painted it with DD alpine green spary paint and looks great no leaks. Bill

[REBrueckner]

All the above advice is good. A few additional comments:

NO NEED TO REMOVE the entire heat exchanger if your interior tubes are clean to your satisfaction...as long as you can reach where you need to clean the exterior.....inspect inside when you get ends off the heat exchanger use a flashlight to get a good view inside...maybe a small mirror. Don't remove that whole thing unless you have clear reason to do so....it's just a container for coolant...

SS bolts in the expansion tank and fittings are fine...they should not touch salt water anyway.

Be SURE to come back after some engine run time, maybe five or ten hours, and tighten up the bolts...you'll likely find they are a lot looser than when you left them. Tighten them uniformly....

Instead of paint primer, try RUST ARRESTOR or NAVAL JELLY black coating....Home Cheapo carries a brand although few employees know where to find it...it's in the PAINT section of their stores....This gunk is gray when applied and turns BLACK upon drying...it turns rust (an oxygen compound) into an inert coating and usually prevents further rust (oxidation). Spray paint over when dry....usually the following day....

When the gaskets are off, try wiping (lightly rubbing) the metal gasket surfaces with a flat mill bastard file...the double etched very fine file pattern....see if you have any high spots...move the file in rotation, like a clock, always keeping it flat against the mating surfaces, as you gently rub...often you'll find a few bright spots...these are high spots that the file is smoothing...no need to go nuts because the soft gasket should take up some of these imperfactions. Sometimes edges of mating surfaces will be concave....edges slightly proud....othertimes a bit of gasket remains unseen.....especially as you get older....

When reassembling, use NEVERSEIZE on the bolt threads...the silver stuff that keeps bolt threads from seizing...if you ever have to get those bolts off again you'll likely find it easy...no broken bolts,etc....

I have used red high temp silicon gasket sealant LIGHTLY applied to each side of gaskets ..so it does not gush out edges....and that has given good service, but maybe there is a newer better product???? Wipe off any exterior excess sealant as paint does not adhere well...

QUESTION: I've owned four 53 series and two 71 series engines and like Bill Allen noted, it's almost always the discharge side of the heat exchangers that weep...have never figured out why...Anybody have a theory?? It should not be related to the pencil zincs insofar as I know....

[rsmith]

"When reassembling, use NEVERSEIZE on the bolt threads"

NEVER I REPEAT NEVER USE NEVERSIEZE! unless it is the marine grade neversieze. the regular neversieze contains disimilar metals that can cause electrolisis in the marine environment. If you cant get the marine grade use the saltwaterproof trailer bearing grease. I don't know why people keep giving out this bad advice. They need to do their reasearch first.

[Bill Allen]

I think it's a couple of things, first of course it's salt water. Second may very well be the heating and cooling in the salt area, diferent expansion rates. The fresh water side warms up and stays warm. The raw water side cools faster and stays cooler While in contact with the warm housing. So i think it's a corrision, and temp issue. In any event at least in my old engines they must have been aware of it since the housing that bolt on are red brass (bronze?) and they used ss bolts. The gasket was rather thin for my taste, but since it's been in there for God only knows how long, it was more then adequate. It would be quite a job to remove the whole housing (and messy) in my engine room. My coolers at ,what I can see, are now spotless. I use a alpine green engine paint and it seems very durable with no drying issues. I do touch them up after I do any work on them as it's easier to spot leaks or issues before they become a problem. Of course since they're my babies I like keeping them nice looking. Bill