Hardin 454 Operating Temp

[Joet5point9]

Recently bought my uncles 91 open bow eliminator jet boat. Boat is in great shape. It has the original Hardin 454 in it, runs solid, but runs at 190-195ish. It does not have the gate valve on the water inlet to adjust water flow like my previous jets. Anyone think this temp is too high?

 

[DarkHorseRacing]

Seems a little hot. Is that just at idle? Does it drop when cruising? It should drop when cruising.

Where was this boat run? Could the cooling system have a lot of debris in it?

This is a good primer on Jet cooling systems:

Tech Talk - Jet Boat Engine Cooling | PerformanceJet.com

Over the years there has been a lot of discussion and misunderstanding with regard to the best method of keeping your jet boat engine plumbed and cooled properly. In this article I will try to explain the problems and solutions to this frequently asked question in the simplest manner possible...

www.performancejet.com

 

[Joet5point9]

Drops slightly to 180-185 while cruising.

Boat is run in Blythe only. I haven’t checkfor debris. Maybe run it in the driveway on the hose?

these are cast heads.

 

[DarkHorseRacing]

Well you can do some checks on your cooling system per the article. ie, follow the hoses from your jet and map out your cooling system to get an idea if its correct or its been modified and not in a good way.

Running it on the hose wont flush out any sand or other river debris, especially if its been in there awhile, most of that crap seems to settle in the block.

One other thing you can check is where the temp sender is for the water temp. Usually its right near the t-stat location on the intake manifold (for GM setups). But it depends how the engine is plumbed to see if that makes a difference in the temp that gets read. Ie: the more the water goes through the headers and engine before going past the sender the hotter it will read, whereas if the sender sees cooler water from the lines before going through some parts it will read cooler.

I'm trying to recall how our jet was plumbed to the engine but its been too long. I sort of recall it came in from the jet, went into the block, then up to the heads, out of the intake manifold, into the exhaust headers and then from there up to the turbo housings and then out the exhaust. Had a second entrance for the oil cooler off the jet. The intercooler was force fed from a pickup in the bottom so it only worked at speed. This was a race setup, so not likely very comparable to your stock Hardin.

 

[JUSTWANNARACE]

They may have a puck(flow reducer) where the thermostat would be!

 

[jetboatperformance]

Very unusual , these boats (unless equipt with a double stack thermostat ) will normally run 100 to maybe 140 , if you need tech help dont heistate a call 7 days a week 804 466 4719 Tom