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From: HiC on 17 Nov 2007 20:11 On Nov 17, 7:09 pm, "Ray O" <rokigawaATtristarassociatesDOTcom> wrote: > Several things can cause an engine to run hot. Check the coolant mix, make > sure the fan shroud and under-engine shrouds are in place, The under-engine shroud was removed when it began to hang due to the screws tearing through. However, it ran for a long time that way with no issue. I wasn't aware it was crucial for cooling, I thought it was for aerodynamics or to protect the engine from debris. The fan shroud is missing a piece that came flying off some time ago that appears to have covered maybe 25% or 30% of the shroud circumference on the bottom, so there's a gap on the bottom. But again, ran that way for some time with no issues. That temp needle used to stay locked to the center. > check to see that > coolant is actually circulating, check ignition timing. When the engine is > indicating hot, shut off the engine and see if the fan clutch is engaged. This may be hard to answer, but how "stiff" should the clutch be when engaged by heat? I'm a bit leery of the fan clutch since that's what appeared to have caused it to overheat necessitating the rebuild to begin with. Had no idea they were that crucial. I just experimented with the engine cold - when I try to give the fan a forceful spin by hand, the amount of resistance sems to vary. It might "spin" only the distance of the space between two of the blades, though on some spins it feels a little looser, maybe moving the distance of 3 or 4 blades. Will have to try it hot. Shouldn't the fan clutch get tighter as the engine gets hotter? This particular fan clutch doesn't have many miles on it. A couple thousand, if that. I had replaced it when I was having overheat problems before and that seemed to cure the problem but apparently the horse was already out of the barn, the head gasket developed issues shortly thereafter. > If you replaced the thermostat yourself, make sure it is properly installed > (orientation of the spring and jiggle valve) Could you elaborate on this? As far as orientation, you mean whether it's in backwards or is there a certain clock orientation where it should be? > and if you used an aftermarket > thermostat, make sure it is also properly seated. > > Check the coolant temperature sensor voltage and associated wiring. Hmm. Any tips on what the reading should be and how it should be checked? It's my understanding that the sensor is the brass piece that has a spade clip and screws in to the side of the thermostat housing, correct? I know that's what makes the temp gauge go limp when removed. One other thing, when I put the new head gasket on, I did notice that the holes on the new Felpro gasket didn't quite match the water jacket ports precisely. There was a certain amount of area that they covered over. Is this likely to be significant? Are they supposed to fit the contour of the water jacket ports precisely? As near as I could tell, there was only one way the gasket would go on and actually fit properly so I'm as close as I can be to 100% sure it's on the right way. Is the only definitive way to tell what the water temp really is to screw in a temp gauge that fits the sensor port and watch it as I drive around? Thanks for all feedback.
From: Ray O on 17 Nov 2007 22:05 "HiC" <brassplyer(a)yahoo.com> wrote in message news:b39b1d4a-f39c-4285-9c36-cc4602a5bdae(a)e1g2000hsh.googlegroups.com... > On Nov 17, 7:09 pm, "Ray O" <rokigawaATtristarassociatesDOTcom> wrote: > >> Several things can cause an engine to run hot. Check the coolant mix, >> make >> sure the fan shroud and under-engine shrouds are in place, > > > > The under-engine shroud was removed when it began to hang due to the > screws tearing through. However, it ran for a long time that way with > no issue. I wasn't aware it was crucial for cooling, I thought it was > for aerodynamics or to protect the engine from debris. > > The fan shroud is missing a piece that came flying off some time ago > that appears to have covered maybe 25% or 30% of the shroud > circumference on the bottom, so there's a gap on the bottom. But > again, ran that way for some time with no issues. That temp needle > used to stay locked to the center. > > The fan shroud and under-engine shroud are important but not critical. >> check to see that >> coolant is actually circulating, check ignition timing. When the engine >> is >> indicating hot, shut off the engine and see if the fan clutch is engaged. > > > This may be hard to answer, but how "stiff" should the clutch be when > engaged by heat? I'm a bit leery of the fan clutch since that's what > appeared to have caused it to overheat necessitating the rebuild to > begin with. Had no idea they were that crucial. > > I just experimented with the engine cold - when I try to give the fan > a forceful spin by hand, the amount of resistance sems to vary. It > might "spin" only the distance of the space between two of the blades, > though on some spins it feels a little looser, maybe moving the > distance of 3 or 4 blades. Will have to try it hot. > > Shouldn't the fan clutch get tighter as the engine gets hotter? > > This particular fan clutch doesn't have many miles on it. A couple > thousand, if that. I had replaced it when I was having overheat > problems before and that seemed to cure the problem but apparently the > horse was already out of the barn, the head gasket developed issues > shortly thereafter. The fan should spin freely when cold with very little resistance. It should be almost locked when the clutch is hot, so yes, it should get tighter as the engine gets hotter. >> If you replaced the thermostat yourself, make sure it is properly >> installed >> (orientation of the spring and jiggle valve) > > > Could you elaborate on this? As far as orientation, you mean whether > it's in backwards or is there a certain clock orientation where it > should be? Generally, the spring should face the engine block. The jiggle valve is basically a hole in the thermostat flange with a piece of metal that looks like it got stuck in the hole. If the thermostat flange is not horizozntal when sitting in the thermostat housing, then the jiggle valve should be at 12 O'clock. Also, as Hachiroku found out, aftermarket thermostats do not always fit snugly in the thermostat housing and can become partly dislodged when the housing cover is installed, causing some wierd problems. > > >> and if you used an aftermarket >> thermostat, make sure it is also properly seated. >> >> Check the coolant temperature sensor voltage and associated wiring. > > > Hmm. Any tips on what the reading should be and how it should be > checked? It's my understanding that the sensor is the brass piece > that has a spade clip and screws in to the side of the thermostat > housing, correct? I know that's what makes the temp gauge go limp > when removed. Sorry, I can never remember and have to look at a manual for voltage readings. Voltage should be low when cold and higher when hot. > > One other thing, when I put the new head gasket on, I did notice that > the holes on the new Felpro gasket didn't quite match the water jacket > ports precisely. There was a certain amount of area that they covered > over. Is this likely to be significant? Are they supposed to fit the > contour of the water jacket ports precisely? As near as I could tell, > there was only one way the gasket would go on and actually fit > properly so I'm as close as I can be to 100% sure it's on the right > way. I suspect that the head gasket may be the source of your problem. The holes shold fit the water jacket ports precisely. If they cover the holes, they will obviously will restrict flow, and the flow of coolant may have softened the gasket material to the point where it collapses when coolant is flowing under pressure. > > Is the only definitive way to tell what the water temp really is to > screw in a temp gauge that fits the sensor port and watch it as I > drive around? That works, or you can remove the radiator cap when the engine is cold, stick a thermometer in the neck, start the engine, and see if the coolant temp matches the thermostat's opening temperature when the coolant starts to flow through the radiator, and if the coolant temp is around 180 ~ 200+ when the instrument gauge indicates normal operating temperature. You will probably lose a little coolant when you do this, so have some extra on hand. Also, make sure you hve the proper coolant mix - too much or too little concentrate can cause overheating. > > > Thanks for all feedback. You're welcome and good luck! -- Ray O (correct punctuation to reply)
From: Hachiroku ハチロク on 18 Nov 2007 11:51 On Sat, 17 Nov 2007 21:05:16 -0600, Ray O wrote: >> Could you elaborate on this? As far as orientation, you mean whether >> it's in backwards or is there a certain clock orientation where it >> should be? > > Generally, the spring should face the engine block. The jiggle valve is > basically a hole in the thermostat flange with a piece of metal that looks > like it got stuck in the hole. If the thermostat flange is not > horizozntal when sitting in the thermostat housing, then the jiggle valve > should be at 12 O'clock. Also, as Hachiroku found out, aftermarket > thermostats do not always fit snugly in the thermostat housing and can > become partly dislodged when the housing cover is installed, causing some > wierd problems. This is true! However, in my case, it was on the Mazda, and was installed vertically instead of horizontally. Why did they do this????? Also, I had to replace a bypass hose last week. It they had moved the nipple on the heater tube three inches forward it would have made the difference between a half an hour to 5 minutes. Remember I said I wanted to punch an engineer in the nose every once in a while? ;) In the case here, I did notice my Supra running a bit warmer without the bottom shroud in place. I had the same trouble HiC did, but I used some cable ties to hold the broken pices in place. It does make a difference. However, in my case, it was also the fan clutch that had gone bad. It looks like HiC covered all of that. Perhaps the thermostat is installed backwards. On one of my Subarus, there is NO WAY to install the t-stat backwards, cause the spring is so damn huge it won't fit backwards! This one has me stumped...it looks like HiC has covered all the bases, unless he's replaced a bad part with a defective part...
From: Ray O on 18 Nov 2007 12:15 "Hachiroku ????" <Trueno(a)AE86.gts> wrote in message news:A4_%i.4491$701.224(a)trndny08... > On Sat, 17 Nov 2007 21:05:16 -0600, Ray O wrote: > >>> Could you elaborate on this? As far as orientation, you mean whether >>> it's in backwards or is there a certain clock orientation where it >>> should be? >> >> Generally, the spring should face the engine block. The jiggle valve is >> basically a hole in the thermostat flange with a piece of metal that >> looks >> like it got stuck in the hole. If the thermostat flange is not >> horizozntal when sitting in the thermostat housing, then the jiggle valve >> should be at 12 O'clock. Also, as Hachiroku found out, aftermarket >> thermostats do not always fit snugly in the thermostat housing and can >> become partly dislodged when the housing cover is installed, causing some >> wierd problems. > > > This is true! However, in my case, it was on the Mazda, and was installed > vertically instead of horizontally. Why did they do this????? Also, I had > to replace a bypass hose last week. It they had moved the nipple on the > heater tube three inches forward it would have made the difference between > a half an hour to 5 minutes. Remember I said I wanted to punch an engineer > in the nose every once in a while? ;) > > In the case here, I did notice my Supra running a bit warmer without the > bottom shroud in place. I had the same trouble HiC did, but I used some > cable ties to hold the broken pices in place. It does make a difference. > However, in my case, it was also the fan clutch that had gone bad. It > looks like HiC covered all of that. Perhaps the thermostat is installed > backwards. > > On one of my Subarus, there is NO WAY to install the t-stat backwards, > cause the spring is so damn huge it won't fit backwards! > > This one has me stumped...it looks like HiC has covered all the bases, > unless he's replaced a bad part with a defective part... > The OP should check the replacement fan clutch operation and also think about the part of the head gasket that is obstructing the cooling jacket holes. Unfortunately, this is not that easy to check :-( -- Ray O (correct punctuation to reply)
From: clifto on 18 Nov 2007 15:52 Hachiroku ???? wrote: > This one has me stumped...it looks like HiC has covered all the bases, > unless he's replaced a bad part with a defective part... He could have something like my problem, where the replacement thermostat has a considerably smaller orifice than the original equipment, but as this is the first time I've ever heard of such a thing let alone had it happen to me, it's a long shot. -- Angry American flags attack Hillary Clinton!
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