Water Temperature won't get hot enough??
 

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

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

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.

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.

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.

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 .

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.

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 ?

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?

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.

If I can't achieve what I'd like with the crossover, then I may go that route. I want to further troubleshoot before going down that path though.
My pressure is at 2-3 psi at idle and it increases accordingly throughout the rpm range up to 24-25 psi at WOT.

Shhhhh. Recirc pumps take less than 10hp to turn just under 6000rpm. I think I saw 4hp loss at 5k. And that was V-Belt's, not serpentine which would be a tad less hp used. Shhhhhh. :)

You'll get some more help on this thread, which you have had good help already, but in meantime do a search of crossover's on this site and you'll see probably 20+ a year. It will give you a good handle on the -'s, +'s, set up differences, and what app's usually have better success using them.

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https://cimg0.ibsrv.net/gimg/www.off...59c71f2361.jpg
This is not my engine, but it's the same setup.
Bottom of crossover is fed from Power Steering Cooler.
Top of crossover feeds the T-housing and bypasses to my headers/risers.

Yes, I have used a IR gun to confirm temperatures.
Temp at the T-housing ranges between 98 to 105 degrees.
Temperature throughout the Intake Manifold is the same.
Temp throughout the entire crossover is around 98.
Temperature on my heads ranges between 114 to 125.

I missed it. Where (exactly) is your coolant temp sensor located ?

Hello SB,

Yes, before registering to this forum that's exactly what I did over the course of the summer, was to search the site for boaters with crossover experience.
Some people had good results, while many others experienced the milkshake issue due to not having a bypass and/or pressure relief valve installed. (separate issue altogether)

There was one individual who pretty much described his lack of heating issue to be the same as mine. However, one day, he decided to remove his thermostat and reinstall it exactly the same, and for some unknown reason his temperature issue went away. He couldn't explain it, but the problem was resolved and he was able to maintain full operating temperature. In his case, regardless of what the issue was (Sticking thermostat, etc.) it sounds like a crossover setup can work properly. So, not all hope is lost.

One individual drilled additional holes into his thermostat and that apparently solved the lack of heating issue. Unless there's an anomaly that I'm unable to comprehend, that just make no sense to me. More holes = more cold water flowing through the block. How does that result in increased temps?

Then of course there's the option of replacing the crossover with a circulating pump. That will be my final option if I can't figure this out. I'm sure that most would just resort to doing this and be done with it. However, I'd like to understand what exactly is responsible for this issue.

Thank you all for your input.

Blair

Right in the intake manifold, about 2" to the left of the T-housing.

Essentially, it's the same as drilling a hole in the thermostat to allow circulation, but by installing the Y at the rear of the intake, you promote circulation from front to back, and of course the volume of water circulating through the block is governed by the size of valve you installed? In your case, I assume that tweaking of the valve is what influenced your overall temperature. Did you still run a thermostat as a contingency for overheating?

Correct. For people using t-stats, that's the beauty of the Merc 4 hose (total) t-stat housing. Recirculates a lot of the warm water back to recirculating pump when t-stat is closed. When t-stat opens it does so thru another (the upper) chamber and out the exhaust. The t-stat operates more smoothly this way to vs opening and closing a schitload of times per minute.

What you described is what I've been speculating to be the case. Just to confirm, you're saying that hot water from the block is exiting from one of the inlet ports and back into the crossover, then out the bypass. Correct?

How did you verify that?

I was thinking of replacing the rad hoses that connect to and from the crossover and to the bypass with transparent/clear rad hose. That would enable me to see the directional flow of water. If there's more volume entering one side of the block than the other, that could be creating a circulation effect, and as the hot water leaves the block it gets pushed out the bypass.

You have an IR Gun, check each leg of the cross over to see if you are experiencing unbalanced flow. I have the same setup and it works perfect, although I added a -10 line from the back of the intake to the front intake cross over to bleed off any steam and to insure good water flow to the heads. I have checked my temps with a good IR gun and my temps are within 1-2 degrees everywhere. What is the water temp you are running in? I was out last weekend in 55* water and idling down the river, I barely got to 115*. Once I got to the lake and pushed it hard it warmed right up. Water temp was 155* and oil temp was 250*. Yes I know my oil cooler is a little small.

The lake temp was 58 on my last and final run.
Crossover temp was 98. Maybe 1 to 2 degrees difference from each end. Head temps are 15 to 20 degrees difference. That's not uncommon, but if yours are within 2 degrees, that's pretty good!

Because you installed a hose from front to back on the manifold to release steam pockets, did you still drill your thermostat?

You will never stabalize with a crossover, some guys have been able to but it's rare, my boat has had no stat and crossover since new in 1987, no issues from it... I tried to re invent wheel like you and now it's back to the way it has been, I have a max of 75 degree water temps and typically less, oil temps 180-190 AFTER cooler, why bother it seems good from factory, I will see 100 water temp maybe at best, 110 at idle after a hard run, don't mess with what works..

If you want Automotive warm up times and higher temps , you will have to put on a Circulator Pump .
The water temps inside an engine , with a crossover , are very uneven at low speeds.

I assume that it is, as the gauge correlates to the IR reading that was taken near the temperature probe.

If it's not too much trouble, when convenient, can you send me a pic of your additional manifold hose?

Sorry, just checked and I don't have any photos of the current configuration. The boat is at my Beach House which is 285 miles away. The worst part is my schedule is so busy, I won't get back up there till the middle of November. I can describe what I did, maybe that will help. I have a Brodix HV2000 intake and it has provisions to drill and tape the intake at the rear where the intake covers the water jacket openings in the cylinder heads. I had it drilled and tapped before I assembled the motor for 1/2" NPT. I installed a -10 - 1/2" NPT 90 in the those new rear ports. At the front on the intake manifold where you have your sensors, I installed 1/2" NPT T's with the side port towards the intake. I then ran a -10 line from the rear to the front and put the sensors in the front facing port of the T's. Hope this helps. All I know is that every time I check engine temps after running it hard, is they are even everywhere, front, back, block, heads. I have a hard time getting it warm when the water is real cold, anything below 60mph and it's below 150*. But once the water gets to 70* it runs right at 155*-160* at any planning speed.

What! You won't drive 285 miles to take some pics for a complete stranger? Lol

Your explanation is clear. Thank you for that.
Separate from my lack of heating issue (issue to me), I like the idea of running a line front to back, it would certainly assist in balancing overall temperature between the heads, block and intake.