pr0wler
20.06.2021 22:31:26
Re: 496 Mag HO exhaust manifold over heat
See full version: 496 Mag HO exhaust manifold over heat
Re: 496 Mag HO exhaust manifold over heat
We sold a 2005 400SS Formula to a customer in Europe and they have issues with the port engine throwing the alarm. The engines are the 496 Mag HO's. Accorning to the Rinda scanner it's both the port and stb side exhaust manifolds overheating in the port engine. The raw waterpump impeller is new, the thermostat is the correct one and new and it looks like the raw water is circulating fine when looking at the through hull exhaust when it's open. The overheating happens only on higher RMP's after about 10 minutes. The temperature gauge it self goes only to about 195 degrees but then the alarm goes off. When they idle and let it cool down it actually goes all the way down to about 155 degrees. The Stb engine stays at steady 180 degrees all the time, idle or high Rpm's. The boat is in Europe so we have no way to go and check it our selves but we would like to help the customer out. Does anyone have any experience in something like this? The boat had about 140 hours when he got it and this started right away. All the help and ideas are welcome. Thanks!
We actually changed the impellers before the boat was shipped and the old ones we still good, no pieces missing. I heard that they never back flushed the cooling system either so it is very much possible that there is crap in the system. I have no idea if the drive was banged in the bottom, it sure didn't look like it when the boat left the states. I'm guessing it is either some crap in the raw water side or possibly a collapsed water intake hose in the gimbal housing. I told them already to look for both so now it's just to wait and see. Thanks for the input. [links]
My first thought would be a piece of an old impeller caught in the oil cooler. You said the impeller is new, were all of the pieces of the old one removed? What is the condition of the fresh water pump housing? is it scored? It doesn't take much wear to drop water pessure. Was the drive banged on the bottom? Sand in the block? [links]
Re: 496 Mag HO exhaust manifold over heat
I was asking about this problem and the PCM codes a year ago and just heard from the customer that the problem was never fixed. Can anyone help?
Set Of BB Manifolds 8.1 / 496 Merc With Stainless Risers With Special Brackets. Stainless Marine now offers its time tested system for the 496, 8.1 Mercruiser Chevy engine. This is the same exhaust manifold that has proven itself time and time again both on the race circuit and on pleasure boats. It is designed with the Hi Torque in mind for both reliability and ease of installation. It, like all Stainless Marine products, carries the best warranty on the market along with the assurance that is made by a company known to stand behind their products. here
8.1 / 496 Merc Stainless Port Riser For Hi Performance With Brackets Built To Fit
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The stock intake manifold can’t meet the air flow demands of your Mercruiser engine in performance applications. Our Cool Gap intake manifold has been engineered for one purpose, maximum airflow and power output in marine applications. Our intake manifold incorporates long, high velocity runners to provide excellent low and mid-range torque levels and a large plenum volume to satisfy the demand for more air at higher RPM’s. Our design keeps the incoming air fuel mixtures cool and dense, producing more power and torque over the entire power band.
We don't offer computer tuning, but we've met lots of good people who do. Check out our tuner list to find a tuner in your area. [links]
Full Throttle Marine dyno tests a series of header options on a 496MAG HO. After installing our 525HO / 496cid Stage 1 marine kit they made 553 horsepower @ 5400RPM!
Our stage 1 marine performance package bumps the 496 / 8.1L to 540 horsepower & 600 ft-lbs of torque.
Want even more power? Our 4.5" stroke crankshaft, forged I-beam connecting rods and forged pistons replace your exisiting rotating assembly adding cubic inches and more power. Direct replacement parts for your stock rotating assembly.
Our products are direct bolt-on replacements for any of these marine applications.
Phone: (856) 582-5222
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