Heat exchanger Flush

[garyd]

On the freq. asked questions section there is a Heat exchanger flush discussion. I tried to post this there but it won't let me so I'll post it here.

I did this procedure with excellent results. Bought the Phosphoric acid at home depot, but it wasn't labeled largely phosphoric you had to look.

I removed the large zinc at the bottom of the exchanger and the small zinc on the oil cooler. I pumped into the large one and returned through the small one.

I used a robber glove and plastic on the very large hose coming out of the heat exchanger to the exhaust, I put the hose back on and used the same clamp. Therefore if it leaked a little it would just go through the water exhaust system.

I could not keep the fluid captive kept losing a fair amount, Until I relised it was going out the dripless bushing hose. Once I clamped that off The fluid in the bucket remained constant and it pumped around for about two hours while I was doing other stuff.

I flushed it all out and looked inside the best I could to find a very clean and shiney Heat exchanger.

This worked great!

This should be added to that post.

 

[MikeP]

Although this procedure is well documented - Karl wrote a very thorough post on the method - and is an excellent one for routine maintanance, I recommend the HEs (and the intercoolers if you have them) be removed for your FIRST cleaning on a recently acquired boat. If you have never removed the HEs or ICs, on your boat then it should be used the next time you are ready to clean them. THis is the only way for you to really know their condition and ensure they are not plugged with various thingies that are NOT affected by the cleaning solution. After that, use the in place method.

You can take them to a radiator shop if you prefer or just do it yourself in a 5 gal bucket. THe solution recommended by DD - Muriatic acid, oxalic acid (and water, of course) - is more aggressive AND more hazardous. But being more aggressive means it can clean better/faster. However, its a simple enough process and with appropriate care is not much of a danger - wear eye protection but you should be doing that with any method of cleaning the HE/ICs.

 

[garyd]

Mike, In the freq asked questions is where Karl put that procedure which I referred to and I also sent him a PM with a tank you LOL

I was just adding some insight that I learned by doing it. By the way it was so easy I would go this route before removing them and taking them to a radiator shop.

If ya flush and the cooling is fine why remove them?

garyd

 

[MikeP]

If ya flush and the cooling is fine why remove them?

It all boils down to what someone is comfortable with I guess. Cleaning in this way, in my mind, is no different than cleaning a carburetor by putting carb cleaner in the fuel or spraying it with carb cleaner - it works fine if the carb is already fairly clean and has no grunge in it. It doesn't work very well if that is not the case.

I pulled/cleaned the HEs and ICs and replaced all the gaskets/glands. From that point, I certainly would feel comfortable with the in-place cleaning but not before. Sure it's more work but it certainly isn't difficult.

Virtually every DD I have seen on an older boat shows signs of at least minor seepage around the gaskets/glands on the HE. If you decide to correct that and replace the gaskets, you're only about 2 more minutes away from pulling the HEs anyhow. Pulling/cleaning them and replacing the gaskets puts it all back to like-new condition which is a good place for a cooling system to be.

 

[captddis]

Believe me, you do not want to remove the stacked plate exchangers that the DDEC engines use, unless it is needed. About 96 allen head bolts. the bolts on the backside are a bit** .

 

[Genesis]

I strongly recommend pulling the H/E cores on mechanical engines every 2-3 years - the other years are fine to run the cleaner solution through.

The primary reason is that the bolts on the end plates can seize, and if they do, you will be VERY unhappy if one snaps off in the cast iron housing!

BTW, do NOT use anti-seize there. Use marine trailer bearing grease on those bolts and be careful not to overtorque them. Anti-seize has copper in it and with exposure to salt water you just created a dandy galvanic corrosion problem!

 

[captddis]

The bolts are about 6 inches long and go into aluminum and or have nuts that are a real treat. It can be a 3 day job on these

 

[Genesis]

Yeah, the DDEC HEs are a real pain in the butt...... just one of many reasons I wouldn't own 'em

 

[captbuddy]

Genesis,
Correct me if I'm wrong but while flushing with your method ( which I did last year with great results), this is only flushing the saltwater side. Don't you still have to take the HE out and take it to a radiator shop to get boiled out. Still haven't done that yet. Can't remember if you described how to DIY on the freshwater side or not.
captbuddy

 

[Genesis]

Yes.

But the FW side should not foul for a very long time UNLESS your coolant additive level goes out of balance, OR you are running something you shouldn't (e.g. coolant full of silicates)

There are "offline" cleaners you can run that allegedly will clean the FW side but I wouldn't mess with them. Pull the cores and take them to a radiator shop for that.

 

[captbuddy]

Thanks Genesis,
My port engine had started running a little hot if I run up to 1800 rpm. Before it was my starboard engine running hotter. I flushed the raw water side of starboard engine and still ran hotter. Polished the fuel with Alge X polishing system my boss bought for himself. While polishing I noticed the filter supposely stopped up in a hurry. Changed filter in polisher and clogged up again. Has auto shut off when vacum gets high. Before polishing fuel I had noticed my vacum gauge on the racor would foul pretty fast after changing filter. Decided to unhook polisher and blow throught the fuel supply line. Surprise, surprise. No more problem with the filters clogging. Now the port engine is heating up. But the vacum gauge is not showing any problems. Staying in the white. This is why I'm thinking the raw water side needs flushing. Am I off base here or what.
Thaks,
captbuddy

 

[Genesis]

Check ALL of the raw water side before you start screwing with the fresh water side. Especially, check the gear coolers!

 

[jim rosenthal]

Amen to that, on the gear coolers....I had gone through this on my CATs and couldn't figure out why one ran warm. Finally took the gear cooler apart and it was incredibly clogged- scale, pieces of old zincs, etc etc. I soaked it in muriatic acid and water and it cleaned up fine. In the CAT arrangement, it is last in line before the showerhead, so any zinc pieces that get loose from the HE zincs end up in the gear cooler (or the showerhead, I guess, if they are small enough).

Anyone know the suggested maintenance interval for taking the showerhead apart?

 

[captbuddy]

I hate to sound stupid but I'm still learning after 3 years of ownership and doing all work on my 453's. Can you tell me where the gear coolers are on the 453's.
captbuddy

 

[yachtsmanbill]

On the 6-71s the engine oil cooler is below the heat exchanger, and the gear cooler is mounted on the block side below that. Its piped off of the oil cooler bypass valve. Dimensionally, it resembles the engine oil cooler. ws

 

[SKYCHENEY]

To find the gear cooler, just follow the oil lines coming from the gear itself. You will see the pump and also somewhere in that loop will be the cooler. I'm not sure, but on a 453, they may just have a loop through the H/E for cooling, but if it is that way you will see the oil lines going to the H/E tank.

 

[captbuddy]

I looked this weekend trying to find the gear cooler. I found something about 5" almost square which is attached to the oil cooler by a 1 7/8 hose out the top of the oil cooler. Then it is attached to the engine block on the side. It does have to high pressure lines attached to it. About 1/2" lines. Checked the manual but can't find a pic.
Thanks,
captbuddy