Why would Gil Manifolds crack?
 

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I need one more set of Gils to complete the parts list to fit two BBCs into my 28' Checkmate. I found these on eBay, and wondered why they would crack in the first place?

Is this normal for Gils?Anybody had this happen to them?
http://cgi.ebay.com/ebaymotors/ws/eB...ayphotohosting

That is a common problem I have had several of our engines full of water over the years with cracked manifolds. If you look at that picture of the manifold you listed it was already repaired on the inside. It looks like bubble gum on there.

I've seen more than one set of Gils fail in that area.

I would look for some stainless marine manifolds.

http://cgi.ebay.com/ebaymotors/STAIN...QQcmdZViewItem

Thanks for the advice, but next time. I've invested in Gil for tails and one set already, otherwise I'd by these from Bad Enough.http://www.offshoreonly.com/forums/s...d.php?t=175626
Here in Ontario, the most common reason for cracking is frost - typically water left in the exhaust maifolds and freezes over the winter.
Do Gils (or any cast) have have a habit of cracking? What stress causes this? The weight of the risers vibrating?

I had two manifolds crack/leak in that area. Don't know why. I still have two sets of old manifolds that I will part out for much less than the ebay add. Maybe shipping plus 100 or so. I will ship the best pair. If you are going to take a crap shoot on old Gils at least get them cheap. I bought new ones from Douglas marine. PM me.

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PM away to Thunder - thanks. Merry Christmas.:cheer:

My Merc/Gil manifolds cracked in the same place.

I lost a motor in my old Fountain because of a failed Gil manifold. Cracked in the same place.

Any idea why? And from the eBay posting it looks like the crack is on the engine side, running on a 45 angle down from the flange...
Must be the stress from vibrating those risers.. anybody ever braced the risers? Anybody cracked Gils while running the Silent Choice pipsqueak, snub risers?
Too bad, as they look like a good option for aftermarket marine exhaust. I'm still going ahead and installing them because of the parts I've already paid for, but I am disappointed they have this reputation.

You live and learn...:mad:

I bought 2 sets used that had beenrun in salt. 1 cracked in the same spot the second year I ran them. I had it fixed and have had no more troubles in 3 years. Irun in fresh water.
I wonder if salt or fresh water makes a dif.

My brother has a set for sale too for BBC. His do not leak, etc.

He has a full custom dry setup for a 22 Donzi classic, with the water dumps past the transom so you don't have to drill holes. He took it off because it was LOUD.

The casting in that area is real thin and can not take excessive heat. I had a problem with them 15 years ago and thay were at the Miami Boat show and at that time they said they were going to change the casting and make it thicker in that area but I don't think it happened.

Tyler, I used to see the same problems...especially on the late model engines that had the fuel pump mounted on the sea pump. Usually the customers wiuldd have a bad fuel pump and then the impellor went bad while they were running and we would have to fix/repail the seals in the pump housing, replace the impeler and fuel pump and the manifolds were junked... Expensive repair for those guys... :(

:cool-smiley-027:So as soon as the impeller went kaput, no water to the manifolds and bingo - the manifolds get so hot they crack?

This situation isn't specific to Gils, is it? I would guess any cast aluminum would suffer under these conditions, including heads...anybody fooled around with an electric water pump as backup?
:evilb:

How about selling your Gils while they're still worth something and finding a deal on Stainless Marine's?

:party-smiley-004:Well, I had one set with long tails included in a package deal from Blown Formula and already had a set of mid-length Gil tails from a previous deal.

I like the weight savings and the design of the Gil flange (with bolts) - the quality of the tails is superb. I don't have any experience with either manufacturer but need to complete the setup, so thought I'd ask for some history lessons.

Thunderstruck is going to sell me at least one set, perhaps two so I have a couple of spares for the ones I break!:hitfan:

NO....the 500's were sold with Gil's back then....so the problem was common...AND the manifold split in the same area that was mentioned above...

We had so many failures with the water pump/fuel pump assembly is was rediculous... it actually got to a point that the housings were on back order and it was hard to get a pump assembly....

Just stating my experience when I did this for a living... nothing more..

The problem is when they break they can take the engine with them. I just don't like to wait for it to happen.

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So, lack of coolant is what causes the Gils to crack...whether by water pump failure or extended "air" time could do it?
If the Gils are real sensitive to coolant presence, I guess this isn't the setup for offshore but more for smooth water racing. This is where the stainless would shine (no pun intended).

How do you guys keep the water pumps together when wave-hopping? I took the seawater pumps apart on the used 454's last week and I'm surprised at how vulnerable they are..isn't there a better design available than this?

Nigel,

The mail box store was closed today so I get shipping costs tomorrow.

Gill Manifolds
 

Thunderstruck - please empty your mailbox, you're full!!I can't PM you.......be sure to ask for ground shipping costs....

The Newer Style Gil Manifolds Seem To Be Alot Better Than The Old One Swith The Freeze Plugs In Them. And If You Are Really Set On Keeping Your Tail Pipes Hardin Marine Sells A Header That Will Fit In Place Of Your Manifold Keeping The Same Tail Pipe. Matt

Wet Exhaust Coolant Flow?
 

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:eek:
When did the design change? Here's what I have, with two more manifold sets on the way from ThunderStruck..I plan to cut the longer tails to accommodate the silent choice diverters. I can't afford to refit with new stainless so I'm piecing together what I need to get up and running in 2008.

I took a look on Hardin Marine's site - nice parts source - and saw orig Merc replacement manifolds but nothing matched the Gil bolt flange, but thanks for the tip, anyway.

If anyone has any coolant line (plumbing) guides, I'd be all eyes and ears - it appears as though the coolant fills the manifolds and then is externally routed to the tails. I guess the closed loop systems would return the coolant from the fittngs at the end of the long tails.

Gil Manifolds
 

A seawater pump mounted improperly will cause inadequate water flow. Not only do hoses have to be on right , but pump must also be positioned or "Clocked" as you will find in a Mercruiser manual(Ie: Definitely in Service Man #9)
A water restriction also is bad news.
I don't know why people still want to run this junk.
They are an "investment" in futility and definite future, if not immediate problems.
Many times a boat owner , mechanic, parts changer etc., will get away with bad manifolds leaking a little water, gradually eroding valve seats or doing subtle damage that takes time to realize if ever understood that the exhaust was the root cause of problems, before repeating the same mistakes over and over with several motor overhauls.
I had bought a set of them. They never ended up on the boat. They themselves were bought cracked and I sent them out to be fixed. I smartened up. They ended up getting scrapped before they wrecked my $12,000 motor.
If there is any area to save money, it's not wise to try doing so with these exhaust manifolds or old headers.
I just saw a 540 Bulldog motor come back to a prominent local builder that was installed by so called proffessionals with these $#!+ manifolds. The shop would not put them on the motor and advised strongly against it. I couldn't agree more. And even worse is the aggrivation that a 40 + year race engine builder gets due to others stupidity and ignorance and not following good advise.
As for exhaust parts, they may be very new, but can get artificially aged due to high heat and heat cycles and related stresses, corrosion and fatigue.
Flush, Flush, Flush.... I can't understand even when someone like my friend who spent about $10,000 just for exhaust doesn't protect his investment. Run fresh water through WITHOUT the motors running if you get back late and don't want to piss off the neighbors.