Blown Head? Cracked Intake? Exhaust riser?

[csanna2]

Im in awe! I have been fighting what seemed a blown head gasket problem. Replacing the head gasket and finally replacing the head all together. Still getting water in the last cyl. Then I bought a new exhaust manifold. Only to still have the same problem. Until I seperated the old exhaust riser from the old intake to find that the exhaust riser was cracked alowing water to sit in the exhaust manifold. I never would have thought in a million years that this was the culprit. I was ecstatit to find the problem, but at the same time depressed when I thought of how many man hours and money I wasted. Has anybody else ran into this problem? 1971 Searay 3.0 mercruiser // pre alpha outdrive Just incase I didnt mention It. THe sypmtoms where a missfire on the last cyl // with signs of water fowling plug out and water presant in the last cyl!

 

[tommays]

Re: Blown Head? Cracked Intake? Exhaust riser?

Did you do a compression check before changeing the head gasket ?<br /><br /><br />The gasket between the manifold and riser is one of the first places to check and it gives you a good idea of how much metal is left on the parts<br /><br /><br />tommays

 

[csanna2]

Re: Blown Head? Cracked Intake? Exhaust riser?

I never did a compresson check. But there wasant a compression problem. Just a bunch of water sitting near or on the rear cyl exhaust valve.<br /><br />I will remember to check the riser from now on. Ive been working on cars all my life. Boats and their funky exhaust/intake manifolds are new to me.....thanks for the repsonse....Have you heard od one of thse risers busting and causing this kind of problem before?

 

[tommays]

Re: Blown Head? Cracked Intake? Exhaust riser?

Its the root of most evil in boats and in saltwater they go every 5 years<br /><br /><br />tommays

 

[csanna2]

Re: Blown Head? Cracked Intake? Exhaust riser?

I would have never thought that the riser would cause a missfire in one cyl! <br />Has anyone else had this problem?

 

[csanna2]

Re: Blown Head? Cracked Intake? Exhaust riser?

Tomray when you say how much metal Is left. Do you mean how thick the metal is?

 

[tommays]

Re: Blown Head? Cracked Intake? Exhaust riser?

<br /><br /><br />

<br /><br /><br />They can leak anywere if enough time goes buy BUT the condition of the metal and cloging in the gasket area will give a pretty good idea of there condition<br /><br />tommays

 

[sailsmanship]

Re: Blown Head? Cracked Intake? Exhaust riser?

I did last year.. Water leaked in and caused hydraulic in the back cylinder causing the rocker arm stud to break. If you have inboards, the water leaking in will go to the back cylinders because of the tilt of the motor.

 

[bruceb58]

Re: Blown Head? Cracked Intake? Exhaust riser?

I had the exact problem with am 87 OMC 305.

 

[I/O WALDO]

Re: Blown Head? Cracked Intake? Exhaust riser?

My 93-502 mag with STAINLESS RISERS Got a crack in one and would hydro-lock 1 bank whenever it was run and then shut off overnite.(Risers would pressure-test fine,so I replaced the mans. first,and reinstalled the tested risers,same problem!! Two new risers,problem gone!)