Here's why my Lehman didn't heat up properly.

[Marco Flamingo]

A recent post went through some of the causes for the engine to not get up to temp. I had some of that problem with the engine only heating up to 170 if I was running the engine at 1800 rpm for some time. If I ran at 1650, it might get there towards the end of an eight hour run. The coolant can pass through the hot water heater and a Red Dot (bus heater), but even with those ball valves shut down it didn't get up to heat.

I bought a new thermostat (180 degree instead of 170) and installed it yesterday. I put my new one in water on the stove and used my IR thermometer to check the opening temp. First cracked open at 175 and kept opening a little after 180. When I pulled out the old one, I did the same thing. The old one first cracked open at 168 and fully open at 175.

When putting the old and the new side by side, I finally noticed what the problem was with the old one.

The old one on the right has a hole drilled in it. It is drilled, not punched, so I think that this is an "aftermarket" modification. Why would somebody want the engine to only heat to 130 for the first several hours? Even when cruising, if I slowed to 1500 the temp would drop. Anyway, issue solved.

 

[rslifkin]

Drilling a small hole in a thermostat to help bleed air out of the system is common. But many people drill the hole too big and cause issues like you found. In my experience, a 1/16" hole is big enough to bleed air and doesn't typically have any noticeable impact on warmup. 1/8" is too big.

 

[jleonard]

Nice to hear about the resolution of a problem especially when it’s an easy one. Good on ya

 

[Comodave]

Can you try to repost the photo? I would like to see what the hole looks like.

 

[Marco Flamingo]

I had this happen before. When I look at my post the picture is there. Apparently not for everybody. Here it is again (maybe) as a link to a picture posted on Dropbox. I need to take picture posting lessons.

Login - Dropbox

 

[Comodave]

You can upload the photo with the box below where you type in your reply to thread. It is in the Additional Options and the attach files button. Your Dropbox link requires a login. Since I don’t do Dropbox it is useless to me.

 

[catalinajack]

I recently swapped 180-degree thermostats for 170-degree. My engine had been operating at 190 degrees and sometimes more which I did not like. After the swap, both engines warm up to 178 degrees (IR thermometer) within a mile of leaving the dock and pretty much stay there. And, I drilled air bleed hold slightly larger than 1/16-inch which, in my case, does not cause a long warmup. Dave, I have no idea why your engines respond differently. I do have one engine plumbed to the water heater which seems to make no difference.

 

[Marco Flamingo]

Let's try this. The hole is on the old (right) thermostat on the left hand side. New one is made in USA. Old says made in England. Original?

 

[Comodave]

Thanks.

 

[Insequent]

I had this happen before. When I look at my post the picture is there. Apparently not for everybody. Here it is again (maybe) as a link to a picture posted on Dropbox. I need to take picture posting lessons.

Here you go:
https://www.trawlerforum.com/forums/s22/how-post-pictures-50850.html

 

[Willin]

Thanks. I have a similar issue on my FL.. silly question but where did you buy your thermostat? Does any std one work or do i need to go to American Marine? Thanks

 

[Choices]

I drill a hole in all my thermostats, about 1/4".

It is a common off-road racing mod. That little hole will get you home if the stat fails, but slowly.

 

[Marco Flamingo]

Thanks. I have a similar issue on my FL.. silly question but where did you buy your thermostat? Does any std one work or do i need to go to American Marine? Thanks

I bought mine off of an Ebay listing that stated that the thermostat was for my particular Ford Leyman, although 180 degree instead of the more standard 170. Somebody had done the research and determined that it would fit my marinized Ford engine. For that "service," I paid $30 for a $10 thermostat. There were other listings that wanted more than $30. I hadn't pulled out the old one yet (wanted to do it quickly), so I couldn't look at it to determine what I really needed before ordering one.

Now that I've gone through the process, I would do it differently. The thermostat fits a 54 millimeter milled inset in the Ford Lehman. That sounds kind of specific, but it is pencils out to 2 1/4 inches. It is a standard size used in older Ford vehicles. In fact, when researching with the new one in hand, it appears that thermostats from older Ford Mustangs are the proper size and come in a variety of different temperatures and even opening sizes. Were I to get another, I would get something like this ($7 with free shipping). I believe all of the SuperStats have a larger than stock opening.

Most of the newer, better thermostats have a tiny "leak" in them to bleed air out. Read a detailed description to find out if the one you look at has this feature. As it turned out, mine did. Once I put the coolant tank back on and refilled they system with the same fluid that I had drained out, it looked like I had too much coolant at first. There were little bubbles coming into the tank and I now realize that they were coming straight up from the thermostat, which is directly underneath the fill cap. I waited a few minutes to add the last couple of cups and I was right back to the original level. I think the SuperStats also have the air bleed feature.

No point drilling a hole in a new thermostat that doesn't need it.

 

[Xsbank]

This hole thing is not an issue. Many new thermostats have a little doo-dad stuck in a hole that kinda-sorta works like a loose valve to let air pass through for bleeding. Ergo bingo, a hole in the thermostat.

Remember to test your coolant annually to look for the correct level of additives and change it out when it fails. Cheap and essential.