Risers getting very hot.

[MSmith3615]

Can someone tell me how I can check and see if I need to replace risers? I recently had manifolds and exhuast elbows replaced. As you probally know I was having a overheating problem. I was under the impression that when shop changed manifolds and elbows they should have changed risers since they are about 20 years old. They seem to be getting way to hot, will boil water. The elbows were rusted out, so could the rust have built up in risers and this is why there getting so hot?

 

[Haut Medoc]

Re: Risers getting very hot.

The part that bolts directly to the exhaust manifold is the riser....If it was not replaced when the manifold was, and is 20 years old then I would do so now....You either have lack of flow from the drive or a restriction of flow.....JK

 

[MSmith3615]

Re: Risers getting very hot.

thanks for quick response, will on muffs there is plenty of water coming out of outdrive, so I think that means good flow. If not then how do I check that? I recently replace impeller. Since new manifolds and elbows risers and manifolds get very hot. I also notice that when I shut down engine after running pretty hard the boat temp goes up to 200. But when I start it back up it quickly cools down to around 140-160 range.

 

[MSmith3615]

Re: Risers getting very hot.

I've been trying to figure out for about a month and don't want to give back to shop. Last time it was in it cost me $2300 and for that I should have gotten new risers.

 

[TilliamWe]

Re: Risers getting very hot.

Any possibility that the hoses have been put on in reverse? We had a 1984 boat with a 260 in it. And the cooling hoses could easily fit two different ways. We hooked it up wrong once,a nd the risers got hot.<br />You SHOULD have gotten new riser when you got new manifolds, but maybe you didn't. What does the shop's repair invoice show?

 

[f_inscreenname]

Re: Risers getting very hot.

What temp thermostat do you have in it. a lot of boats like 140* thermostats. That should keep you around 160*. Also when run hard temp will jump up 10 or 20* and come back down. That is normal. <br /> PS Your exhaust is only as good as its weakest link.

 

[MSmith3615]

Re: Risers getting very hot.

How could I tell if the hoses where on wrong? The boat has a 260 in it. the risers are 100% the original ones. When I had the work done I was still learning alot about the whole riser manifold, exhuast elbows thing. Basiclly the 2300 went towards new manifolds, elbows, impeller, complete tune-up, and labor. I think the thermostat is a 160*, I did read somewhere where it should be a 140. I asked the service tech about it and he said 160 was ok.

 

[TilliamWe]

Re: Risers getting very hot.

you probably need the service manual for your engine. It would have the schematic of the cooling hoses.<br />Post your serial # here or on another thread, and I know Don or others will tell you exactly which manual you need.

 

[MSmith3615]

Re: Risers getting very hot.

Does anyone have a schematic of the cooling hoses for my 260? Its an 85 merc 260, outdrive serial number is A442223, the engine serial number is A345557