5.7L Manifold / Riser replacement

[joeybobo]

Hi all,

I have a 2000 5.7L EFI (Serial: #OL651960). I bought my boat used 1 year ago(1st boat), and I'm just coming up to speed on riser/manifold maintenance. I recently just installed new thermostat because I seem to be running a little hot since last year, maybe 5-10 degrees consistently hotter. Temp gauge says 170-175. Since I don't know the previous engine history, I'm just going to assume the risers and manifolds haven't been replaced and am just going to do it. I have 3 questions.

1.) Is 170 at idle -175/180 at WOT considered hot or normal?

2.) I currently have the wet joint design. If I replace both the manifolds and risers, can I just do a straight swap and put the new dry joint style in? I am raw water cooled throughout, running in saltwater, although I believe the previous owner was mainly fresh/brackish running.

3.) Any recommendations on manifolds/risers and merchants? The choices of replacement parts and merchants seem to be endless.

Thanks in advance!

 

[Don S]

Re: 5.7L Manifold / Riser replacement

Have you checked/replaced the impeller yet?

 

[joeybobo]

Re: 5.7L Manifold / Riser replacement

Have you checked/replaced the impeller yet?

Yup, impeller was replaced last year.

 

[dingdongs]

Re: 5.7L Manifold / Riser replacement

it may be better to just remove both 4 the time being and see if they're gummed up with rust which may just require a good descaling.it may only cost you a set of gaskets and a good afternoon of your time and at least you wont be just throwing parts at the boat.even a partially opening thermostat may be all the problem is.

 

[Don S]

Re: 5.7L Manifold / Riser replacement

Don't even think about cleaning/descaling/whatever you want to call it, the insides of the elbows or manifolds. If they are plugged up that is those parts saying "We're done, time to replace us". If you clean them out the next thing they say is "Hey look at us, we just killed your engine"