Thermostat leak
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Elder User
Joined: Oct 2003
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From: Seattle
Thermostat leak
I have a real problem with 2000 Ranger, after changing the upper radiator hose and thermostat, I now have a pretty constant leak from the gasket between the thermostat body and engine. Appears to be something that is triggered by the thermostat opening, so whatever the leak, the thermostat is blocking it.
I've changed the gasket, cleaned the mounting surface as good as I could. Tried re-torquing the bolts, but on that score - what is the torque specs for the 2000 3.0 liter Ranger?
But ultimately, what the heck is wrong here? This should be a pretty brainless operation really. Am I tightening the connection too much and cracking the gasket? I guess that has just occurred to me, although the gasket is not as stiff as a typical fiber gasket is.
I've changed the gasket, cleaned the mounting surface as good as I could. Tried re-torquing the bolts, but on that score - what is the torque specs for the 2000 3.0 liter Ranger?
But ultimately, what the heck is wrong here? This should be a pretty brainless operation really. Am I tightening the connection too much and cracking the gasket? I guess that has just occurred to me, although the gasket is not as stiff as a typical fiber gasket is.
Post Fiend
Joined: Jan 2003
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From: Connecticut
Torque specs for those bolts are 15-22lb/ft (20-30Nm).
You might try a thin coat of appropriate RTV to supplement the gasket.
Is the t-stat installed in the proper direction (spring-side facing down toward engine)?
You might try a thin coat of appropriate RTV to supplement the gasket.
Is the t-stat installed in the proper direction (spring-side facing down toward engine)?
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Elder User
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From: Seattle
Thermostat's in the right direction. The thermostat is jammed in there pretty tight (I couldn't move it when I replaced the gasket the 2nd time), I'm wondering if the thermostat might be the source of the problem - like maybe it's in there cockeyed or off-center.
Edit: Should the thermostat sit under or over the gasket? That is, what is the order of placement - engine, gasket, thermostat, thermostat housing?
Probably my only solution at this point is to buy a new thermostat and gasket, and replace everything again. At least I know there's nothing magical about the job. 22 ft-lbs is nothing for a bolt that big.
The other possibility that I am considering is that old gasket material got wedged into the bolt holes and they aren't fully seating the housing even though it feels like it when tightening them down. Might have to scrape out the bolt holes and use a shop vac to suck out any old gasket material.
Edit: Should the thermostat sit under or over the gasket? That is, what is the order of placement - engine, gasket, thermostat, thermostat housing?
Probably my only solution at this point is to buy a new thermostat and gasket, and replace everything again. At least I know there's nothing magical about the job. 22 ft-lbs is nothing for a bolt that big.
The other possibility that I am considering is that old gasket material got wedged into the bolt holes and they aren't fully seating the housing even though it feels like it when tightening them down. Might have to scrape out the bolt holes and use a shop vac to suck out any old gasket material.
Logistics Pro
Joined: Jan 2002
Posts: 4,907
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From: suburban atlanta
You might want to look at one or both of the housing bolts. Their holes may be bored through allowing coolant to seep down the threads. I sort of remember putting sealant on the threads when I changed my thermostat.
The gasket should be the only thing between the housing and the cylinder head. The thermostat should be sitting in the housing, held in place by the bendable tabs. Some thermostats have a rubber O-ring or seal on the outlet end, towards the upper radiator hose, that should fit snugly into the thermostat housing. That rubber is what makes the seal that allows the thermostat to stop the flow of coolant when the stat is closed.
If your housing is corroded or deformed on the mating surface, you can do a red-neck fly cut to resurface by rubbing it on a flat concrete surface - gently. Sometimes that can polish the gasket surface and make it even so it will successfully seal.
tom
The gasket should be the only thing between the housing and the cylinder head. The thermostat should be sitting in the housing, held in place by the bendable tabs. Some thermostats have a rubber O-ring or seal on the outlet end, towards the upper radiator hose, that should fit snugly into the thermostat housing. That rubber is what makes the seal that allows the thermostat to stop the flow of coolant when the stat is closed.
If your housing is corroded or deformed on the mating surface, you can do a red-neck fly cut to resurface by rubbing it on a flat concrete surface - gently. Sometimes that can polish the gasket surface and make it even so it will successfully seal.
tom
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Elder User
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From: Seattle
Thanks for the input guys. I'll have to shelve this until the weekend, but I'll let you know how it goes when I get it going.
At the very least I'll need to get a new thermostat and gasket.
FWIW: Sanding down the thermostat housing would be a bad idea. There is a small lip on the housing that allows it to bite into the gasket. Sanding it down would remove that lip.
At the very least I'll need to get a new thermostat and gasket.
FWIW: Sanding down the thermostat housing would be a bad idea. There is a small lip on the housing that allows it to bite into the gasket. Sanding it down would remove that lip.
Cargo Master
Joined: Feb 2002
Posts: 2,414
Likes: 22
From: Tucson USA
dont know about yours but you can get a replacement tstat housing at least for mine cheap and not have to worry. Check a parts house for a new one.
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Logistics Pro
Joined: Jan 2002
Posts: 4,907
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From: suburban atlanta
The lip may be there for some purpose, but it is not necessary for the gasket to seal effectively. When I changed my timing belt, I poked a hole in my housing with a flat blade screwdriver during removal. I had to get a new one from the local parts house. The original was sheet metal, the replacement a casting. The sheet metal one without the lip lasted ~20 years without leaking. I think it is a 'belt & suspenders' thing, left over from historical gasket material problems where a gasket needed that tiny lip to make an impression in the surface. The ones I have seen are almost always so small as to seem a defect rather than a significant part of the sealing.
I have done 'surface reconditioning' on thermostat housings successfully for a long time, but you are welcome to use or not use the idea.
tom
I have done 'surface reconditioning' on thermostat housings successfully for a long time, but you are welcome to use or not use the idea.
tom
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Elder User
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From: Seattle
Okay I'm in the home stretch now. I have a last question.
I think I figured out my problem the first time - I didn't realize that the thermostat has a locator on it and I mistakenly jammed it into the housing, torqued it down, and pretty much ruined the thermostat. The housing seems okay, I checked it for flatness and it appears to hold its shape.
I removed the old one, removed the gasket, cleaned the surfaces with lacquer thinner (as recommended), fit the new thermostat into the housing, making sure to reference the locator in the right spot.
Everything seems fine - except..... The gasket has 2 sides, a normal gasket side and a sticky side. Which side goes where?
My assumption here is that the sticky side goes against the thermostat, to hold it in place to make installing the housing easier. But as you can see I've missed the obvious before.
I think I figured out my problem the first time - I didn't realize that the thermostat has a locator on it and I mistakenly jammed it into the housing, torqued it down, and pretty much ruined the thermostat. The housing seems okay, I checked it for flatness and it appears to hold its shape.
I removed the old one, removed the gasket, cleaned the surfaces with lacquer thinner (as recommended), fit the new thermostat into the housing, making sure to reference the locator in the right spot.
Everything seems fine - except..... The gasket has 2 sides, a normal gasket side and a sticky side. Which side goes where?
My assumption here is that the sticky side goes against the thermostat, to hold it in place to make installing the housing easier. But as you can see I've missed the obvious before.
Logistics Pro
Joined: Jan 2002
Posts: 4,907
Likes: 39
From: suburban atlanta
If the thermostat is installed into housing, it should stay all by itself. Your choice on which side gets the sticky. I would stick it to the engine so the holes were definitely lined up, then place the housing and thread the bolts. I thought the new thermostat had a rubber ring that more or less sealed the flow and held the stat in place.
tom
tom
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Elder User
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From: Seattle
A search on, oddly enough, Corvette sites, reveals that the sticky side typically goes on the housing - but as I think you suspect it doesn't really matter. I pulled the trigger and put it on the housing to keep the thermostat in place while I got everything put back.
The seal appears to be holding, idled it until it warmed up last night and did not notice any leaks. Took it for a drive this morning to get breakfast and it still appears dry. I'll watch it like a hawk this weekend while I run errands and call it good if I can make it through the weekend without leaks.
I think I got it figured out finally. Obviously mashing the thermostat into the housing wasn't the smartest thing to do. I think the problem for me was that the bottom of the thermostat is round, only the top has the locator on it. So if you didn't know it was there you wouldn't necessarily be looking for it. But not paying attention is no excuse.
The seal appears to be holding, idled it until it warmed up last night and did not notice any leaks. Took it for a drive this morning to get breakfast and it still appears dry. I'll watch it like a hawk this weekend while I run errands and call it good if I can make it through the weekend without leaks.
I think I got it figured out finally. Obviously mashing the thermostat into the housing wasn't the smartest thing to do. I think the problem for me was that the bottom of the thermostat is round, only the top has the locator on it. So if you didn't know it was there you wouldn't necessarily be looking for it. But not paying attention is no excuse.
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