Bavanew

Hello everyone,
I'm new to the forum, and I actually created an account in hopes of solving my water temp issue.
Note: I've searched the forum to see if a similar problem and solution has already been posted, but to no avail. I've come across very similar issues, but none that solve the issue I'm experiencing.

Background: I have a 97 Baja, Boss 232 with a carbed 509 BBC. I had the engine built and dyno tuned 2 years ago. It's a dart block with Aluminum Edelbrock RPM Heads.
I'm not sure about the CAM or its LSA, as it was removed from the previous engine when I bought the boat. When I had the new engine built I kept the cam, and the build shop was supposed to spec it out for me, but they never did. However, I do that it's a bit aggressive as I cannot achieve more than 7 to 8 inches of vacuum at 850 - 900 RPM. It puts out a respectable 570 HP at 5,200 RPM. The engine and exhaust are cooled by a raw water pump, which flows in the following order: Water pump -oil cooler - power steering cooler - engine block via a crossover - Exhaust / headers via bypass and via manifold thermostat.

Problem: My water temperature will not exceed 110 degrees on a hot day (160 degree thermostat) On a cool day (60 degrees C) I can't get the temperature above 100. As well, I couldn't get my oil temp above 140 at WOT. To correct that I installed an oil thermostat two weeks ago. Following the install I took the boat for a 40 min rip, but couldn't get the water temp above 110 (73 outside) but did manage to get the oil to 198 - 200. Seeing as I took care of the oil issue, I decided that I would tackle the water temp issue.
Note: My original thermostat, which I replaced yesterday, had a 1/4" hole drilled through it, which was for the purpose of preventing any steam pockets /airlock due to the lack of a circulating pump, and my crossover setup.
My thought process was, perhaps there were too many holes drilled into the thermostat, thus allowing too much water to bypass the thermostat, and therefore, preventing full operating temperature from being achieved. Alternatively, the thermostat could have been defective and opening too soon. So, I purchased a new 140 degree thermostat and drilled one 1/8" hole through the thermostat (One hole to start.). However, when I removed the old thermostat, to my surprise, it only had one 1/4" hole drilled through it, and it was rated at 160 degrees. I was expecting to see several drilled holes. And because it was rated for 160 and not 140 as I thought it was, my low water temperature issue seemed even more puzzling.

Anyway, I installed the new 140 thermostat with one drilled 1/8" hole and went for another ride. (That was yesterday BTW.) Guess what? It didn't make one once of difference, the water temp was just under 100 degrees. Also, it's worth noting that I haven't been relying solely on my temp gauge, I've also been using an IR thermometer to confirm temperatures.
Yesterday wasn't exactly the warmest day to be testing water temps as it was 58 degrees out. However, and in my opinion, so long as there's a thermostat in place, what difference should it make if the lake water is colder? Sure, it'll take longer for the engine to heat up the water, but it'll eventually reach full operating temp.

I've come to two conclusions:
1. The amount of water that bypasses the thermostat via the 1/8" drilled hole is generating enough water circulation to prevent the water from achieving full temp. My water pressure is around 15 psi at say, 3,500 rpm and it borders 25 psi at WOT. Is that enough pressure to force enough volume of water through the 1/8" orifice to prevent full temp from being achieved? If that's the case, then it makes sense that colder lake water will have an affect on overall water temp as cold water is continuously being introduced into the engine.
Yet, I've heard it said by others who have a similar or identical setup to mine, that they can achieved full operating temp and they have three or four 1/8" hole drilled through the thermostat. So that contradicts my theory. I was tempted to try a non drilled thermostat, however, I did not want to risk creating a hot spot in the engine.

2. Is it possible that water is flowing through one side (port or starboard) of the crossover into the engine and out the other side of the engine back into the crossover, then up and out through the bypass? That would certainly create circulation throughout the block. The water pressure pushing into the engine should be even at both inlets, but water does find the route of least resistance. I took multiple temperature readings at the thermostat housing, the crossover, the crossover bypass, the water hoses feeding the crossover, and all the temp readings were between 85 and 105. I was expecting the water temperature pre crossover to be closer to the lake temp. Albeit, seeing as the water first passes through the oil cooler and PS cooler, that would explain why its warm when by the time it reaches the crossover, however, with the amount of water volume that flows through the bypass and into the exhaust, I can't imagine it being that warm, especially with cold lake water. Nevertheless, that's what it was.

Anyway, I've provided as much detail that I can think of at the moment. Has anyone experienced this before? If so,what was the resolve? (Not including the installation of a circulation pump.)

Thank you for your time!

Blair

AllDodge

iTrader: (1)

Which thermostat housing is installed and if its the one in the link, are all parts installed as shown?

https://www.mercruiserparts.com/bam/...31912/4854/130

ICDEDPPL

iTrader: (1)

It`s not a car engine as long as oil temp is good then forget about the water temp. My temp gauges never move off 100* . you`re trying to solve a non problem.

Bavanew

Despite the fact that 100 degree water temperature is a non issue, there is still an issue, as it should be able to climb to 140 degrees, or whatever the thermostat is calibrated to.
I want to understand why this is happening rather than to just accept it for no apparent reason.

Secondly, and as you pointed out, oil temperature is important. Water temp and oil temp are relative to one another. The quicker your water temp heats up, the quicker your oil heats up. When my water temp reaches 100 degrees, my oil temp is within a few degrees of that. However, once my water temp stops rising, the rate of increase for oil temperature slows down significantly.
If I can get my water temperature up to 140 degrees, then my oil temperature will also reach 140 degrees much sooner than if the water temp only reaches 100. That's ultimately what I'm trying to achieve, is a quicker heat up time.

I idle the engine for 5 minutes to warm it up enough to idle smoothly. Then I have to run the boat for 10 min to get the oil and water to 100 degrees. Then I have to run it for an additional 20 minutes to get the oil to 140. Even with the oil thermostat, it takes about 40 min to get the oil to 190-200. (That's running at 3,500 -3,800 rpm)

If I can knock 10 minutes off the wait time to heat my oil by increasing my water temp, then I certainly will if it's at all possible. If it ends up being that I can't improve it, then so be it.

Bavanew

It's not an OEM part. I'm not sure what manufacturer it's from as it was with the boat when I purchased it.

I tried to include a pic, but the site won't allow me to post an attachment until I have 10 posts.

ICDEDPPL

iTrader: (1)

As soon as mine hits 120* oil and I can get on plane (10 minutes) I don`t worry about it after that, oil temp climbs pretty quick after on plane.
I don`t know why your engine isn`t reaching temp but it`s not the 1/8 hole. if the stat is truly closed it doesn`t make sense why it`s not getting hotter inside the engine.
If you do get it to 140* you might be here next week trying to figure out how to lower your 250* oil temp .


Good luck, I`ve never ran a stat so I can`t really help .

Bavanew

The odd thing is, when the engine was first built, the mod shop told me they had a difficult time regulating the engine temp. They said it would climb to about 155 then drop quickly to 100, then repeat. That's when they drilled the T-stat.
I had assumed that the T-stat already had a hole drilled into it to prevent airlocks, and therefore assumed that they just added additional holes to regulate the temp. Since I've had the boat the temps has averaged between 100 and 110, depending on the weather.

When I removed the thermostat the other day, (as I said earlier) there was only one hole drilled through it. In hindsight, I now know that there was no hole in the T-stat when they were able to get the temp up to 155. (Unless they're lying about that, which would make no sense.) And the only thing they did was to drill one 1/4" hole, which regulated the temp to the 100 degree range.
A single 1/4" hole was responsible for lowering the temps from 155 to 100. Does that sound realistic?

As for a 250 oil temp issue, that's always a possibility. Lol However, I won't know until next spring as I winterized the boat yesterday. I thought by replacing the T-stat I would have resolved my last known issue before putting it into storage.
Alas, I still have an issue to resolve in the spring.
Figured I'd get an early start by joining this forum.

The only other thing that I can think of, is that the thermostat is not being pressed down firmly into the manifold by the housing. Perhaps it's lifting from its seat ever so slightly, allowing water to bypass.

MILD THUNDER

iTrader: (3)

If youre set on running a thermostat, id ditch the crossover, go with a circulating pump and mercury thermostat housing setup.

What kind of water pressure are you seeing ?

AllDodge

iTrader: (1)

Going to need to see your setup. Can do another quick post (post 5, post 6, etc) or post pic elsewhere and link here

Have temps been check with IR temp gun at the thermostat?

mike tkach

iTrader: (3)

100 % agree,the circulating pump will reduce the speed the water enters thus cools the engine.i have seen a lot of issues with running a t stat with a crossover,one of these issues it to much water pressure.