Thermostat question

[MANIC MECHANIC]

I just ran my jetboat after installing a thermostat kit from Rex Marine on my 454.
I also tossed the old exhaust and replaced it with a set of logs.
I have the 5/8 hoses routed according to the diagram supplied with the kit.
The motor ran dead cold before the kit except at idle.
Now it runs around 180*at moderate RPMs
but if I floor it, the temp gauge begins climbing and continues to climb until I let off. Went almost to 240* once.
Also.... is it normal to have some steam out the exhaust tip with logs after a hard run?
Any input would be appreciated.
Tim

[GlastronGuy]

Are there any holes drilled in the thermostat?

[MANIC MECHANIC]

I have heard about drilling additional bypass holes.
I thought that was for if temps climbed at idle.....I'm pretty steady at 180* at idle or moderate RPMs...
Tim

[MidnightMantra]

I'm having just the opposite problem, I installed the thermostat system and cant get my temperature no higher than 120. I also installed a 20 psi bypass regulator from Hi-Tech. Can anyone give me some insight on how to get my temp up to 160-180??

[1 fast okie]

i had the same problem with over heating then realized that i had it plumbed wrong i forget but one of the diagrams is wrong make sure the hoses from the block tee go into the top openings of the t-stat housing, i also run a bypass valve , have a incoming gate vavle that is about 3/4 open and leave the the block dump line completly open if you have a vavle on it i've done this same set up on three of my freinds boats and it works perfect .

[Rexone]

Double check your plumbing. The thermo opens at 160 and dumps full water flow at that point. Your top temp should never go above 180-190 if you have unrestricted flow. The "bottom" two ports on the t-housing should be your dump lines either overboard or to your exhaust risers or headers with a tee etc. If you have restriced the flow through those lines that could be the problem. I have seen this happen many times.
You could have a bad thermo but in all my years selling these I've never seen a bad new thermo. Doesn't mean it can't happen.
When the thermo is closed it bypasses all water through the upper chamber of the housing and out through those 2 lower ports.

[AgentX85239]

I just installed the thermo kit, tested it out and forgot to open my old valve I was using all the way. Temp went up to 200+ (steam coming out of exhaust) but once I opened the valve it stayed around 150-160. Also when I installed the thermo I ran new hose and cleaned a lot of junk out of the T coming from the intake (was really gummed up). Here's a pic of the front of my plumbing (not too pretty) -
http://home.earthlink.net/~agentx85239/motorsmall.jpg

[Nubbs]

I installed the REX thermostat last year and haven't had any problems with it. My temp stays about 160, and mayble climbs to 180 at idle.
Nubbs

[MANIC MECHANIC]

I double checked my hose routing today... it's all correct.
Everything is hosed with 5/8 hose and the appropriate fitting...
with the exception of the fitting in the bottom of the risers.
I already knew that the water fittings in the risers were a little smaller than everything else, but when I tried to remove them, they obviously were going to collapse so I decided I'd never get them out and keeping my fingers crossed.... installed the logs as they were. (try turning a wrench with your fingers crossed!)
Now I feel like I HAVE to get the fittings out and hope that replacing them with a larger fitting will solve the problem.
Thanks for the replies and I'll let you know what I find out.
Tim

[Nubbs]

Is it possible you have the thermostat in upside down?

[Rexone]

If it ran cold using those fittings before the thermo install those fittings cannot be the problem Tim. Something else is limiting your flow. The thermo when operating normally does not limit flow from pre-thermo enough to make any difference. Did you change any other aspect of your plumbing when you did the thermo install? Also is the thermo installed in the correct direction inside the housing? That's important for opening properly. I'm just trying to get basic here because most problems turn out to be basics overlooked. I'm confident it's something like this as we've sold literally thousands of these units that operate flawlessly.
If no plumbing changes my next step would be to put the thermostat in pan of water on the stove and heat er up and watch it to see if it opens all the way. It should open far before boiling of the water (160º). If it does you've eliminated that as a possible cause. If you don't test that you will be hunting and hunting always wondering if it could be the thermo not opening. That is what I'd do first since its an easy test.
I don't think your riser fittings are the cause if they worked before they should still work.

[MidnightMantra]

Question, my temperature is only getting up too 120 degrees with the thermostat system. I am also running a 20 psi bypass regulator before going into the thermostat. On my first outing last weekend I had my inlet valve from the pump wide open. If I close is some will it assist in raising my temperature up to 160?

[Rexone]

Originally posted by MidnightMantra
Question, my temperature is only getting up too 120 degrees with the thermostat system. I am also running a 20 psi bypass regulator before going into the thermostat. On my first outing last weekend I had my inlet valve from the pump wide open. If I close is some will it assist in raising my temperature up to 160?
If you are continually cracking the 20 lb bypass you are in effect circumventing the thermostat by allowing continual flow of colder water in, hence the thermo never opens (never reaches 160º).
I suspect you have this bypass mounted on the engine itself. Try moving it to the inlet line (tee) prior to getting to the engine. If that's the case it should eliminate the no heat problem by bypassing cold water before it ever gets to the engine while still controlling any excess pressure your pump may be producing.
Closing the inlet valve is always a bad idea to control temp IMO because of the reduced flow it produces in idle conditions which then causes overheat, thermo or no thermo.

[Brooski]

If anyone can help me, I've two questions. What pressure does a Berkeley pump produce in the inlet water line to the engine (at full throttle), and at what pressure does the Bassett T-valve start to open?

[LVjetboy]

Brooski, the inlet line pressure at full throttle depends on pump rpm, line sizes, valve and fitting restrictions, so I can't give you an exact number. But typically you may see 30-40 psi free flow with a mild engine at full throttle. A pressure gage is a good investment. The T-valve opens at a very low pressure, something on the order of a psi or so if I remember right. Doesn't take much. Why do you ask?
jer

[Brooski]

Thanks for the info. It is mainly out of curiosity. I have a '76 Southwind 18', which I just changed out the Ford BB with a Chevy 454 that used to run logs. Now I use headers. To achieve an engine temp close to 160-180, the inlet valve from the jet needs to be only 1/4 open, and I dont feel comfortable with the valve closed that much. I was reading where some people use a pressure restricter on the inlet side, and was wondering what the pressure was without one. My inlet hoses are 3/4".

[Taylorman]

I have a pressure gauge on my intake and when i used to use the t valve it would open at about 5 psi.

[LVjetboy]

I'd recommend a pressure gage like Taylorman or electric dampened on the dash. Only way to know for sure. I used to run the Rex T-stat and adjusted flow to 180 max at idle. Served me well for many a year. Now I run free flow at 150 idle and 120 full throttle...one season so far. My pressure full throttle (6200 rpm) is 20 psi. This is within seal limits on my engine so no regulator...but my cooling lines and restrictions are likely different than yours. On my old 454 setup I saw 35 psi at 5000 with the inlet full open.
Oil temperature may be more important than water in the end. And even with a water temp of 120, you can bet oil gets hot in a jet. With the T-stat, your running temp should hold steady but idle temp depends on you valve setting. Put a gage on and adjust your flow so you don't overpressure seals but have sufficient idle flow to stay at or below 180.
For header injection, electrics are by far the best. If you don't want electric, the Bassett valve works ok, but not great. To get steam at 2k, you'll probably see some water out the holes at idle just because of the valve design. I'd recommend a separate 1/4" ball valve for each header line, that way you can both balance flow and adjust overall opening rpm independent of engine coolant flow. The old Bassett valve problems/with spring breaks from ball oscillation, I've heard they fixed that but not sure. Just in case you may want to mount easy to get to.
jer

[Aluminum Squirt]

I'm a little confused. Here's my system and I haven't run it yet. Hopefully this gets me in the ball park with no pressure problems/hot spots. Pump->hi-tech pressure regulator->oil cooler->brass T->2 x front of motor->Rex T stat->dual dumps out the side. All plumbing is 3/4 until the brass T and from there its 5/8 to the front of the motor, through the t stat and out the dumps. Headers are dry. Obviously some testing will give me some numbers but I wanted to make sure that the regulator is not going to be detrimental to the function of the Rex T stat. I run almost exclusively at WOT. Thanx-Aluminum Squirt
www.eagleracing.ca/Forum/viewtopic.php?t=3481
The above link (2nd and 3rd picture down)show a couple of pics of the regulator as it comes in the boat and my motor on the ground with the Rex T stat. Hope I got it right and no clowning on the duct tape on the roll bar....its just in mock-up phase :)

[MANIC MECHANIC]

I did not get time to work on the boat tonight,
But will be giving it hell tomorrow night.
At the same time that I installed the thermostat system
I replaced the rusted out headers with a 3 1/2" log system that I bought used, as I stated before the fittings in the bottom of the
risers are kinda small even for 1/2" hose (everything else in the system is 5/8"hose and appropriate fittings). I tried to get the smaller fittings out but since they were gonna be SOB's I decided to run it the way the riser was already plumbed...
Could this small restriction be my problem?
My plans for tomorrow:
Change fittings in risers to the 5/8" fittings out of the old exhaust system.
Pull out the part of the original hose and tee that I reused and make sure they are clear.
Remove the thermostat to make sure it's assembled properly.
Check the opening point of the thermostat on the stove.
Any other suggestions?
Thanks for the help and the other questions brought up by this thread are interesting.
Do I need to look into a pressure reducing valve for my cooling system?
Tim

[Rexone]

Originally posted by MANIC MECHANIC
Could this small restriction be my problem?
My plans for tomorrow:
Change fittings in risers to the 5/8" fittings out of the old exhaust system.
Pull out the part of the original hose and tee that I reused and make sure they are clear.
Remove the thermostat to make sure it's assembled properly.
Check the opening point of the thermostat on the stove.
Any other suggestions?
Thanks for the help and the other questions brought up by this thread are interesting.
Do I need to look into a pressure reducing valve for my cooling system?
Tim
Yes it could be the problem given the above added information. Anything that restricts flow significantly from the way it was before can have an effect.
I think your plan is logical and a good one to find the problem in an orderly manner.
On the last question, you will only know the answer if you install at least a temporary pressure gauge and check it. Every system is different. Being that you're overheating though my guess is you don't have excessive pressure. But it is a guess.
:)

[MANIC MECHANIC]

Today I determined that the hoses and tee are clear.
So is the steel line coming from the pump.
The thermostat is assembled properly, and opens
at 160*.
Changed the fittings in the logs and will let you know how it does first chance I have to get it on the water, probably sunday.
Thanks for all the help.:)
Tim

[MANIC MECHANIC]

I finally got a chance to run the boat today.
Apparently the restrictive fittings in the risers were the problem as it cycled between 160* and 180* all day, full throttle, no problem!
Thanks for the help!
Tim