97 Volvo Manifold replacement?...Opinions Needed.

[bruceb58]

1997 Volvo 7.4L 160 Hours. First put into service 5/99. Engine has 170 Hours of which 100 hours are in salt water.<br /><br />Decide to take off the risers today to take a look on how things were. Nothing was acting improperly...just preventive maintance. I did not see any rust streaks on the inside of the exhaust manifold.<br /><br />Now for a couple photos!<br /><br />First the riser. Very clogged up it appears. This photo was after I pressure washed it to remove most of the loose crud. I am going to replace this for sure.<br /><br />

<br /><br />Now for the manifold...It had similar crud in the openings. After pressure wash, most of the crud is gone...walls look very intact...some rust deposits still but doesn't look too bad.<br /><br />

<br /><br />What are your opinions on this manifold? Should I just go ahead and replace it since it is out? Aftermarket manifolds are not available for this motor so Volvo is the only replacement option.<br /><br />Thanks,<br />Bruce

 

[rodbolt]

Re: 97 Volvo Manifold replacement?...Opinions Needed.

compare the cost of the engine to the cost of the manifolds and decide if your dice are gonna come up 3's or 7's.<br /> saltwater cares more about time than operating hours.<br />cast Iron is incredibly porous, leave them on the bench a week and you will still see water bleeding from it.

 

[Bondo]

Re: 97 Volvo Manifold replacement?...Opinions Needed.

Ayuh,.......<br />The Riser is JUNK,....... <br />The Gasket surface on the wall between the Water,+ the Exhaust is 50% to 90% Gone in several places.........<br /><br />The Manifolds don't look awhole lot Better......<br /><br />I'd say you got Lucky, finding them Now,.. Instead of Later........<br /><br />I sure Wouldn't put them Back On........<br /><br />But,..... Like Rodbolt Says,.........<br /><br />Roll the Dice,....... Ya feelin' Lucky....??..........

 

[bruceb58]

Re: 97 Volvo Manifold replacement?...Opinions Needed.

Out of curiosity, what is the thickness of the walls of a new manifold? I measured around and found this one varies fron 0.340" to 0.273". The 0.273" is measure in the bottom right hand corner.

 

[Scaaty]

Re: 97 Volvo Manifold replacement?...Opinions Needed.

Its down on the bottom of the manifold where the problem begins, where you can't see it. I had a Man let go last year, and was only getting water into one cylinder, and I still don't know why it didn't seep into the adjacent cylinder (middle 2). Had the man up on the bench, plugged it, filled with water, and never leaked a drop. But I put all new stuff on, and it's fine now. Sometimes you just cant see what the problem until its too late. Anyway, once in salt, replace after 4 years unless you really flush it out every time out, and use saltaway. Your on 7 years...buy new.

 

[bruceb58]

Re: 97 Volvo Manifold replacement?...Opinions Needed.

I am going to buy the new manifolds. <br /><br />I bought the boat with 65 hours on it and those 65 hours were all salt water. I am religious about flushing the motor but not sure about the previous owner. Figuring that even if I kept these manifolds, I would be replacing then within 2 years anyway, I may as well replace them now since they are off and i can have a little more peace of mind.

 

[bruceb58]

Re: 97 Volvo Manifold replacement?...Opinions Needed.

What is the best aftermarket manufacturer for the riser? Manifold has to come from Volvo but I have more options for the riser. Should I just get a Volvo riser?

 

[rob935]

Re: 97 Volvo Manifold replacement?...Opinions Needed.

be carefull i just replaced both manifolds and gaskets on my 4.3 vp only to have one of the risers let me down by leaking into the cylinders, hydro locked knocked teeth outta starter and had to take manifolds off AGAIN and replace riser...dam lucky i didnt do any lasting damage to the engine

 

[bruceb58]

Re: 97 Volvo Manifold replacement?...Opinions Needed.

New riser and manifolds?

 

[Scaaty]

Re: 97 Volvo Manifold replacement?...Opinions Needed.

Originally posted by bruceb58:<br /> What is the best aftermarket manufacturer for the riser? Manifold has to come from Volvo but I have more options for the riser. Should I just get a Volvo riser?

Best is original, but ebay has some good people that sell mans and risers that are the same quality for much less.

 

[Bondo]

Re: 97 Volvo Manifold replacement?...Opinions Needed.

In the picture above,.....<br />The Riser is in Worse shape than the Manifold.....<br /><br />You're Not dealing with How Thick the walls are in these things,....... It's the Gasket Surfaces........<br /><br />In the Top picture,.... Lower right-hand corner,.... Bottom-side,... The Gasket Surface, between the Water,+ the Exhaust,..<br /><br />I can SEE a Rust Pit that goes Nearly 1/2 Way THRU the Gasket Surface.........<br />The Left-side has 2 Huge pits going Better than 1/2 way thru,......Lower left corner is Just About Thru.......<br />The Top-side is BAD for Most of it's length........<br /><br />Ayuh,...... You Need a Matched Set,..... Manifolds,..And Risers..........

 

[bruceb58]

Re: 97 Volvo Manifold replacement?...Opinions Needed.

Bondo,<br /><br />I think what you are describing on the riser is the gasket that I didn't scrape off. <br /><br />On the riser, what I felt was knocking it out of commision, was mainly how clogged it looked. The actual mating surface on both manifold and riser looked pretty good.<br /><br />The gasket surface on the manny is perfectly smooth. Only place that I thought was marginal was the lower right corner where the thickness measures at 0.270".<br /><br />Since I don't want to deal with this again in 2 years, I am going to replace the matched set and go with Volvo for both. I just spoke to a dealer that claims that wall thickness of the aftermarket Sierra, Barr and Osco risers is a lot thinner than Volvo and can't tolerate an overheat event as well. Anybody weighed these to see what the difference is?

 

[rob935]

Re: 97 Volvo Manifold replacement?...Opinions Needed.

i got parts from glm far cheaper than volvo parts and exactly the same, just be sure not to accept paper manifolds

 

[rob935]

Re: 97 Volvo Manifold replacement?...Opinions Needed.

the glm manifolds are exactly same weight, dont know about the build quality but im sure difference in price is just for Volvo brand name...?? ive just sold my boat so im not thinking 2 years down the road...its your call good luck!!

 

[Bondo]

Re: 97 Volvo Manifold replacement?...Opinions Needed.

I Live on Lake Ontario,....... Manifolds,+ Risers Last for EVER..........<br /><br />The Only time I see replacements sold is because of Freeze Damage...........<br /><br />I bought a set of GLMs from a Friend,...... I didn't Weigh them,....I Like the design,....<br />The Fit,+ Finish is Good,... I know they're Chinese.....<br />Time will Tell,....... I got 6 Years,+ 640hrs. out of a Frozen set that I welded up.......<br />I figured I'd been Rolling the Dice for Too Long..........<br /><br />Good Luck with Your's..........

 

[bruceb58]

Re: 97 Volvo Manifold replacement?...Opinions Needed.

I just ordered new Volvo everything yesterday. I just figured that even if they have 1/4 of their life left, that only works out to $100/manifold. With my time changing them out plus peace of mind, I felt it was worth buying new ones now.<br /><br />I did take them to a dealer for his opinion. He felt the mating surface to risers was good, pressure tested ok but did say it is a crap shoot regarding areas you can't see.