Replacing Risers & Exhaust Pipes

SupremeWake · Soul Rider Joined: 14 Feb 2003 Posts: 322

How often are you replacing your exhaust systems, including risers? I've noticed some corrosion and rust pieces when I drain mine for the winter. How do you know when its time to replace them? I guess when the exhaust starts filling up the engine cover eh? Laughing

BMontgomery · Criminal Joined: 21 Jan 2003 Posts: 55 City: Baytown,TX

IF YOU RUN IN FRESH WATER, YOUR RISERS AND MANIFOLDS SHOULD LAST 6 OR 8 YEARS. SALT WATER MAYBE 3 OR 4. IT'S VERY IMPORTANT THAT YOUR RISER GASKETS ARE IN EXCELLENT SHAPE BECAUSE THEY KEEP WATER OUT OF YOUR ENGINE. TAKE YOUR RISERS OFF AND CHECK TO SEE IF THE CAVITIES ARE CLOGGED WITH RUST. IF THEY ARE IN BAD SHAPE CHANGE THEM. THE WALLS WILL RUST THROUGH CAUSING WATER IN THE ENGINE BLOCK.

SupremeWake · Soul Rider Joined: 14 Feb 2003 Posts: 322

Ok. I've never taken them off before so I'm not sure what I'll be looking at inside. I'm assuming there will be a gasket sealing the riser to the engine and this is what I should make sure is in good shape as well as the interior walls of the riser itself?

If the cavities are clogged with rust can I clean the rust out and re-use the risers as long as the walls aren't rusted through and maybe replace the gaskets if needed?

thanks,
dan

BMontgomery · Criminal Joined: 21 Jan 2003 Posts: 55 City: Baytown,TX

YOUR MANIFOLDS ARE BOLTED TO YOUR HEAD CASTING. YOUR RISERS ARE BOLTED TO THE TOP OF THE MANIFOLDS. THERE ARE FOUR BOLTS HOLDING EACH RISER. JUST TAKE THEM OFF AND INSPECT THE INSIDE. YOU CAN FLUSH THEM OUT AND SCRAPE THE RUST OUT OF THE CAVITIES, BUT MAKE SURE THAT THEY ARE SOLID. THE RISER GASKET WILL HAVE TO BE REPLACED, THEY ARE ABOUT 4 DOLLARS EACH. tAKE THE MANIFOLDS OFF ALSO. THERE ARE 8 BOLTS HOLDING EACH ONE, BUT BE CAREFUL NOT TO BREAK A BOLT OFF. SPRAY SOME PENETRATING OIL ON THE BOLTS TO LUBRICATE THEM. RINSE THE MANIFOLDS OUT WITH WATER AND INSPECT FOR RUST.

tryan · Soul Rider Joined: 06 Feb 2003 Posts: 257

the stock pcm risers lasted 30 years on the nautique. if your are anal 'like me' you oil them up when you winterize.

the rise to manifold gasket goes in a particular way. this is to make sure the cooling water gets circulated properly over the top of the riser.

SupremeWake · Soul Rider Joined: 14 Feb 2003 Posts: 322

Thanks fellas,

I'll go take em apart now since I have the day off and the wife and baby are both asleep! Smile

Tryan...30 years!! wow... I believe I have the stock PCM risers on my 351. I don't know if the previous owner ever replaced them or not...guess I'll find out soon enough. What do you oil them with, fogging oil I assume?

Also, what do you mean "the rise to manifold gasket goes in a particular way"? Will it be obvious once I see it apart or should I know more before doing it?

thanks,

SupremeWake · Soul Rider Joined: 14 Feb 2003 Posts: 322

...having trouble getting the 4 riser bolts off. there isn't enough room to get a socket or a wrench on them? Not sure what to do. Is there a special tool ?

BMontgomery · Criminal Joined: 21 Jan 2003 Posts: 55 City: Baytown,TX

JUST USE A BOX END WRENCH. YOU CAN ONLY TURN THE BOLT A LITTLE EACH TIME, SO IT'S TEDIOUS.

tryan · Soul Rider Joined: 06 Feb 2003 Posts: 257

if the risers blow , your motor will sound odd. if the manifold blows it can screw up the motor.

pb blaster and heat will get bolts loose. breaking them off sucks.

skidim sells a complete riser kit. bolts, gaskets everything fo 70 bucks. stainless hardware lasts the longest. summit sells copper gaskets for the truley anal. ( who me? )

put the riser gasket in the right way.

use copper never sieze on the bolts.

check the proper torque specs. 25 ft #'s rings a bell.

the manifolds on the 72 are still holding strong after 30 years.(the first center riser manifolds made.) the manifolds on the 1960 graymarine are also solid.

wesgardner · Posted: Nov 20, 2003 6:58 pm Post subject:

Hey tryan,

Graymarine, now there's a name I haven't heard in a few years....

Wes

wesgardner · Posted: Nov 20, 2003 6:58 pm Post subject:

Hey tryan,

Graymarine, now there's a name I haven't heard in a few years....

Wes

tryan · Soul Rider Joined: 06 Feb 2003 Posts: 257

gray is owned by teledyne and still has millions in parts for the older models.

yup , a boxed end of the only thing that will fit. years of paint will get in the way. you can grind the perimiter off a cheap wrench if it is still tight.

yes, i fog the innards with fogging oil durring the winter. dads old 73 landcruiser exhaust manifold caught on fire while tying to remove as broken stud. cast metal sucks up the oil for some reason.

the gasket between the riser and the manifold should be blocked at the back of the riser. the open hole should direct the flow over the top of the riser.