Stupid Intercooler

[Liquid Asset]

We now know the cause of our engine failure was because of somethign I least expected. The intercooler, which was just pressure tested and rebuilt by the radiator shop in november sprung a saltwater leak somewhere and sent saltwater through the airbox. Which in turn caused it to seize while sitting for 2 weeks. What wounderful news that was. Guess it happens sometimes, but it sucks.

 

[REBrueckner]

That does sound unusual..at least I sure hope it is REALLY unusual because I just had mine off the stb eng..found one had a slight leak...it was replaced.

To my knowledge, intercooloers can't be "rebuilt" only replaced.

 

[bobk]

I sure hate to have to ask this question, but what is the difference between an inter cooler and an after cooler? My 6V92's are TA I think..... 425 HP. Are these also raw water cooled? I had them pulled and cleaned last fall, but never thought to have them tested. God, I'd like to have naturals....(Lehman SP135's.. ahhh).

Bob

 

[yachtsmanbill]

I'm a little better off with 12-71Ns but they are soo gigantic that I would trade for a pair of 400 hp six bangers. All that cooling business really takes some of the fun out of it IMHO. ws

 

[Genesis]

Aftercoolers sit in the airbox and are cooled with engine coolent. Intercoolers are between the blower and the turbo and are cooled with sea water.

Aftercoolers should last the life of the engine if coolant balance is maintained. They do need to be removed and the air side cleaned every few years, and its a pain in the ass as you have to remove the blower to get to it (plus drain the cooling system)

 

[bobk]

Aftercoolers should last the life of the engine if coolant balance is maintained. They do need to be removed and the air side cleaned every few years, and its a pain in the ass as you have to remove the blower to get to it (plus drain the cooling system)

Yep, that's what my mech did last fall. I had him tune it up too since he was almost there. Every three years..?

Bob

 

[Genesis]

Yeah, that's about right.

A tune-up by the way is MANDATORY if you disturb the blower mounting, because the control rods coming out of the governor will have their alignment changed when the blower is dismounted and remounted.

THIS IS NOT OPTIONAL - a significant bank imbalance is the likely result if you just slap the blower back on and don't run the rack!

The "no rippie apart" way to know how fouled your aftercooler happens to be is to stick a set of pressure gauges on the engine - one on the airbox drain and one on the airhorn port (so you have a measure on BOTH sides of the aftercooler.) Now go for a nice hard run and see what 'ya got for pressure differential at WOT.

If the airbox pressure is higher by a couple of PSI than the airhorn pressure, the aftercooler is likely ok.

If its equal, its marginal.

If its lower, you need to get in there and clean it now.

Unfortunately there is no way to know if you have gunk on it inhibiting heat transfer without causing a pressure differential problem, so even if this test comes up "clean" I'd recommend pulling it every 2-3 years. But this test is one that I'd perform annually, since its very easy to do and requires only two $30 gauges plus some hose to accomplish.

 

[MikeP]

I wonder why DD went to aftercoolers? Was it for performance or just manufacturing conveniance? An AC version could be used in anything whereas the IC version could only be used for marine. Anyone know?
Were all '92s AC and all (turboed) '71s IC?

Doesn't really matter - just curious.

 

[captddis]

A Intercooler is a maintenance item and they do deteriorate over time. Thats why I replace them when doing overhauls. Of course they are expensive and none of the people who go for the low bid jobs get them replaced. However when they fail, it is often catastrophic. Rods through the side etc.
Almost all the on road and industrial high output engines are aftercooled. Marine can have either and in the case of the 6V92 TIA, it has both.

 

[Genesis]

Aftercoolers maintain a MUCH more stable temperature because the cooler has coolant in it rather than raw water. Raw water can vary from just over freezing to as high as 90F in temperature, while coolant is typically regulated within 10 degrees F.

This allows better control of engine internal temperatures and a more stable operating environment for the motor.

In short, its a superior solution. However, because the space allowed is fixed by the size of the airbox, the amount of cooling available is also fixed.

Then of course there's the "it shouldn't ever leak and destroy the motor" side of it, which is a big deal too.

The downside is that its a royal pain in the tush to get to it in order to clean the thing, and because its the coldest thing in the path anything that CAN condense on it, WILL condense on it. Like oil mist, suspended carbon if you have an exhaust leak or are station-wagoning, etc.

 

[bobk]

Re: Stupid Intercooler/station-wagoning

The downside is that its a royal pain in the tush to get to it in order to clean the thing, and because its the coldest thing in the path anything that CAN condense on it, WILL condense on it. Like oil mist, suspended carbon if you have an exhaust leak or are station-wagoning, etc.

Back to station-wagoning, can any one suggest a way to eliminate this on a series I 48MY with full enclosures?


Bob

 

[MikeP]

If you have forward hatches that can be opened to allow air to run the length of the boat and exit from the rear, it will eliminate the "backdraft" as long as the boat is moving fast enough to ensure a good flow of air.

THere's really no way to eliminate the fact that the shape of the boat causes it. Any object, from bullets to boats moving through the air produces the effect. Amusingly enough, "Boat Tail" bullets were designed to reduce that drag effect. Which it does. Unfortunately, power boats don't have "boat tails."