4" heat exch end caps, flat or concave?

[billywhizz]

i have 485 merc with a 4" heat exchanger, the cap at the intake end keeps leaking,
i tried various sealer new rubber etc, but no luck still leaking,
the caps are flat but when i look on the internet the pics show what apears to be slightly concave/dome shaped caps, this leak is worse since i replaced the impeller, how can i find out if i have the wrong caps?
or what dictates the caps being flat or dome? thanks guys

 

[Don S]

Re: 4" heat exch end caps, flat or concave?

If it's leaking, replace the caps and gaskets.
OEM is usually slightly domed. Aftermarket are flat.

 

[billywhizz]

Re: 4" heat exch end caps, flat or concave?

If it's leaking, replace the caps and gaskets.
OEM is usually slightly domed. Aftermarket are flat.

Ok Don, will do, thanks for the info,
here,s a more technical question, my exchanger is divided into three chambers, some of the tubes from the chamber where the sea water comes in move over to the middle chamber,
and some of the tubes from the middle chamber move over to the chamber where the sea exits, if i use the OEM domed caps as we should, some of the water will cross over to the next chambers without going down the tubes, am i correct?

 

[billywhizz]

Re: 4" heat exch end caps, flat or concave?

Still no joy, I replaced the cap and gasket with new and still it squirts water past the gasket, iits like the pressure from the impeller is greater than the exchanger can cope with,
it only blows at the raw water inlet end of the exchanger, i bought the exchanger second hand and had it shipped over, i am now wondering if the guy sent the wrong end cap/caps?
It is a 4" three pass exchanger, can anyone say for sure what shape the end cap should be? flat or dome?
I should add, the whole exchanger is spotless all tubes clear and no blockages anywhere on the exhaust system.

 

[cr2k]

Re: 4" heat exch end caps, flat or concave?

Have you checked the end of the exchanger for flatness or any nicks or gouges?
Or even if they are square to the tube?

 

[solar7647]

Re: 4" heat exch end caps, flat or concave?

Still no joy, I replaced the cap and gasket with new and still it squirts water past the gasket, iits like the pressure from the impeller is greater than the exchanger can cope with,
it only blows at the raw water inlet end of the exchanger, i bought the exchanger second hand and had it shipped over, i am now wondering if the guy sent the wrong end cap/caps?
It is a 4" three pass exchanger, can anyone say for sure what shape the end cap should be? flat or dome?

The caps on mine are flat and work fine.
Take the cap off and see if there is any damage to either the cap or the rim of the heat exchanger.

Also on mine both side of the cap are the same, its just a flat round piece of aluminum. If you can try to use the other side of the cap and see if the works, I had to do it once because of the cap bowing and the gasket going bad.

I also made my own gasket using over the counter rubber gasket sheet from auto store, I just cut a circle out of it the size of the cap and cut a hole in the center for the bolt.

 

[billywhizz]

Re: 4" heat exch end caps, flat or concave?

Have you checked the end of the exchanger for flatness or any nicks or gouges?
Or even if they are square to the tube?

Yes, checked that with a steel edge, all good, the plate and the gasket seats good.

 

[billywhizz]

Re: 4" heat exch end caps, flat or concave?

The caps on mine are flat and work fine.
Take the cap off and see if there is any damage to either the cap or the rim of the heat exchanger

thanks for the reply, is yours 3 or single pass?

 

[solar7647]

Re: 4" heat exch end caps, flat or concave?

Not a 100% sure what you mean by pass but if you mean the number of chambers that are in the exchanger the answer is three

 

[pcmpete]

Re: 4" heat exch end caps, flat or concave?

maybe your hose from exchanger to riser is blocked, creating too much pressure, just a thought

 

[EddiePetty]

Re: 4" heat exch end caps, flat or concave?

.....I bought the exchanger second hand and had it shipped over, I am now wondering if the guy sent the wrong end cap/caps?
It is a 4" three pass exchanger, can anyone say for sure what shape the end cap should be? flat or dome?

ALL CONCERNED:
Please note that "billywhizz" has specified that he has procured a multi-pass heat exchanger. In order to re-direct the cooling water through the tube bundles, the endbells (caps) must be dome-shaped and have partitions between each group of pass tubes. (Certainly some of you former Navy guys have seen a main condenser opened before!...same concept).
Personally, I have only seen single pass heat exchangers in Mercruiser. I have previously advised Billy that certainly he has an exchanger similar to those found on sea-going diesel engines.
To answer Billy's question.......Domed end bells (with partions and gaskets to matech) are required for multi-pass exchangers (coolers).

Ed in 'ol Virginny