Heat Exchange End Cap leaking worse after replacing gaskets

[ddclapp]

Hi all. I have 1984 Mercuiser 260, close cooling. One of the gaskets on the end of my heat exchanger started spraying all over the place. So I went to my local dealer and bought two new round rubber gaskets (sierra replacments). They were quite a bit thicker than the original that I had on (maybe twice as much). So I put them on, tested and looked good so I headed out. As soon as I put the boat in the water and fired up they both started spraying all over the place!

What is going on! I tried to tighten them more but it just got worse! There are multiple streams going every where! I made sure both sides were clean and mostly smooth before putting them on. Do I need different gaskets? These are round rubber disks 1/16 inch thick. Should I put some sealant on them?

 

[500dollar744ti]

post a picture of where the leak is coming from?

 

[cr2k]

Maybe take a file and make sure they are flat.

 

[ddclapp]

This leak is right at the end caps- you could see it spraying out the right by the gasket. I tried over tightening and it got worse. It seems I need another type of gasket or some sealant? I could try filing as you suggest cr2k - it just does not make sense they were working before and not with new fresh gaskets...

 

[Bt Doctur]

remove them and turn them around or re-flatten them and don't tighten them so tight this time.

 

[Bondo]

remove them and turn them around or re-flatten them and don't tighten them so tight this time.

Ayuh,...... Agreed,.... Take 'em off, flip 'em over, 'n put 'em back on,....

Tighten 'em just snug enough it don't leak, which ain't very tight,....

 

[ddclapp]

Thanks for all your input. Here is an update. My particular end caps have a small ridge, around the inner edge - I think for helping to compress and seal to the thin gasket that was on previously. Because of this there is right "side" for clamping to the heat exchanger, and I cannot flip the piece over, unfortunately. It also has a countersunk area where it bolts in place and about 30 years of paint coats.

So I found a piece of flat steel for a test and put it as a flat surface as a replacement to the original-and wah lah! It seems to work just fine with the new thicker gaskets.

So I think I need to find some 4" end caps that are just flat and smooth and I might be in business?! Are these "normally" smooth?