Perkins 6.354 blowing radiator hoses.

It seems like it one thing after another. I was headed back from the island and blew a radiator hose up top. I had another boat with me so I ran in town and got another. Started back and another one started to blow up like a softball I kept going and made it. At the slip I replaced that one and the hose on the sea pump started to swell up.
Starting to think I have a blockage some where.

Anyone have any dealings like this. I drove it home from Houston and never had a problem. I believe someone was looking after me. Thanks for any help.

Is it a turbo? Could your after cooler then have a hole in it and your pressurizing the system? But, I thought the coolant tank cap would have a pressure relief of a couple pounds to prevent this. . .if this is the case, then your hoses might have been on there last legs. I would at least say that's the case with the seawater pump hose. They only put out a couple psi. If completely blocked on the output side, the rubber pumps vanes just collapse on the compression side and do nothing. Just my two cents! I made some assumptions here, my experience is mostly gas motors and non turbos

Non turbo but I forgot to say, my old sea water pump was leaking so I replaced it with a new one. I kept the old one to be rebuilt and have for a spare

Perish the thought, head or exhaust manifold gasket leaking?

Timetraveler said:

It seems like it one thing after another. I was headed back from the island and blew a radiator hose up top. I had another boat with me so I ran in town and got another. Started back and another one started to blow up like a softball I kept going and made it. At the slip I replaced that one and the hose on the sea pump started to swell up.
Starting to think I have a blockage some where.

Anyone have any dealings like this. I drove it home from Houston and never had a problem. I believe someone was looking after me. Thanks for any help.

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TimeTraveler, I hate to bring it up-but have you considered a leaking head gasket adding compression gases to the cooling system? Chances are- if this is the case, you will large bubbles coming out of the filler neck if you remove the cap and start the engine.

I would suspect excessive buildup causing a restriction in the RW outlet path. First I'd run Barnacle Buster through it and retest. If no change, look into the RW outlet path.

A flexible impeller pump in the raw water cooling system will not generate very high shutoff discharge head. SAY, 100' or 45psi would be a pretty good estimate.

Reading post #1, did this happen first with 2 hoses on the FW side, and then with one on the raw water side? I`m no mechanic, but to my mind they are not supposed to communicate. A failed head gasket should not affect the RW side, unless there is communication going on somewhere, which could be the cause.

Not big on coincidences, but did you buy a lottery ticket?
Seriously, what is the coolant side temps? Should be less than 200F.
Does the exhaust water discharge flow look normal?
Do you have a long plume of white water vapor coming out of the exhaust?

I'd suggest you start by replacing the radiator cap. It should be releasing pressure before hoses start blowing up like balloons. It may be a cheap & easy fix.

Not clear if it was a freshwater hose, sea water hose or some of each...

If freshwater hose blew, radiator cap should have vented pressure before things blew. Not uncommon for the vent port on the side of the cap fitting to plug up on some engines, not sure about this one. If that port plugs, pressure can build above cap rating. It is easy enough to check. Take cap off and make sure the port off to the side is clear.

Ski in NC said:

...Not uncommon for the vent port on the side of the cap fitting to plug up on some engines, not sure about this one. If that port plugs, pressure can build above cap rating. It is easy enough to check. Take cap off and make sure the port off to the side is clear.

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That`s exactly what the mechanic found on both my engines today, tipped off by muck under the cap. Mine are FLs, there is a metal tube inside the tank leading to the overflow tube, set ups vary, but clearing the tube is important or the cooling system tries to vent the pressure elsewhere.

AusCan said:

I'd suggest you start by replacing the radiator cap. It should be releasing pressure before hoses start blowing up like balloons. It may be a cheap & easy fix.

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I agree.

AusCan said:

I'd suggest you start by replacing the radiator cap. It should be releasing pressure before hoses start blowing up like balloons....

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If pressure overcomes the cap spring and opens it, coolant gets access to the overflow outlet in the cap housing. If the outlet is blocked by a build up of debris, nothing can pass down it and pressure relief is frustrated. Thus the posts above about checking the outlet and associated piping.
An old cap is more likely to allow coolant escape, via a weakened spring and leaky seal gasket, than a new replacement.

OP initial comment was that he blew an upper radiator (coolant) hose. This was repaired then a second coolant (I believe) hose swelled up. I took this to mean the fresh water cooling system was at issue-
A blown head gasket/ cracked head could give these results.

BTW if you see upper or lower fresh water coolant hoses collapse and squeeze together after cooling off- this is also an indication of a defective radiator cap- just a different issue. It indicates the small round center is sticking closed and not drawing air or coolant back in as the coolant cools and contracts.


Forky
1983 Present 42 Sundeck
Twin Lehman 135's

OK, I didn't read it the same way. I thought it was a RW side problem. What he described as a "sea pump" I read as RW pump.

Yea Al- I'm not really sure either with that comment. A hose swelling on the raw water pump could only be a raw water hose.


Forky
1983 Present 42 Sundeck
Twin Lehman 135's

Most older boats use pressure caps of well under 5psi.

Perhaps a modern car cap was stuck on, 15psi.

It could also be the coolant system was not purged of air when refilled.

Easiest , is to leave OFF the pressure cap during the warm up period.

Once the thermostat opens all the water passages should fill and the cap can be replaced.

Fresh water side or Raw water side??? I guess we will have to wait and see.

I've had this happen on the RW water side on the 6-354's several times from restrictions in the water system.

Once it was left over bits of old impeller blades caught in the water inlet to the oil cooler on my current boat.

On commercial fishing boats, same engine, it was sediment scale built up in the 3/4" bronze cross over pipe between the cooler discharge and the exhaust manifold. A third instance a piece of scale, about the size of a quarter, dislodged inside the cast iron exhaust manifold and blocked the water outlet to the exhaust elbow.

Never had it happen on the coolant side.

Forkliftt said:

....BTW if you see upper or lower fresh water coolant hoses collapse and squeeze together after cooling off- this is also an indication of a defective radiator cap- just a different issue. It indicates the small round center is sticking closed and not drawing air or coolant back in as the coolant cools and contracts.

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Thanks. That explains it! A few years a go I had this issue and never figured it out. I have since replaced the cap. Now I know what caused it.

Still working on it

High wire your comment is right on. There is a white vapor or color to the water coming out of the exhaust. It is on the sea water side. The radiator cap is not on right now it was rusted and I am in the process of finding one.
When I ran it last the water and antifreeze in the radiator was not moving at all, should there be some water movement in there.

Thank you for the post. The water coming out has a white tint to it

"When I ran it last the water and antifreeze in the radiator was not moving at all, should there be some water movement in there."

Not much to see till the thermostat opens and lets the coolant flow .

Thanks for all the help. It seems my exhaust elbow is getting clogged up.

I had a restriction that cleared up beautifully with Barnacle Buster. I circulated it through the RW components for 4 hrs. My engine temps dropped from 195 F to 165 F on that engine. I'm finishing the other engine tomorrow.

Maybe if can help your engine, too. Only about $75 for a gallon of concentrate - enough for me to do both my engines.