When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
It just occurred to me that water pumps have/had a "weep hole", it leaks coolant when the pump starts going bad as a warning and to pinpoint the source. If your engine has this feature, it's worth feeling around on the underside of the water pump for wetness. If it is the pump, it will eventually make noise as the wear gets worse. Some engines have the water pump blocking access to the timing chain/belt. So, it was common practice to change the water pump when changing the timing belt. Timing chains have a much longer life. If you have a chain, it's possible the pump is original and at your high mileage, a likely culprit. Perhaps someone with more specific knowledge of this situation would care to comment.
It just occurred to me that water pumps have/had a "weep hole", it leaks coolant when the pump starts going bad as a warning and to pinpoint the source. If your engine has this feature, it's worth feeling around on the underside of the water pump for wetness. If it is the pump, it will eventually make noise as the wear gets worse. Some engines have the water pump blocking access to the timing chain/belt. So, it was common practice to change the water pump when changing the timing belt. Timing chains have a much longer life. If you have a chain, it's possible the pump is original and at your high mileage, a likely culprit. Perhaps someone with more specific knowledge of this situation would care to comment.
The timing belt and water pump were done at a Lexus dealership at 97k miles (now at 142k). However, that was more than 15 years ago in June of "06 (45k miles in more than 15 yrs?? I have my suspicions about the odometer). The LS400 has a belt and regardless of mileage I think I'll do it while I have it apart due to age. Also noticed what I believe to be power steering fluid all over the place now that I have it up and the under cover off and getting up close and personal with it. So, let's see.... radiator hoses, radiator, power steering (pump? lines? we'll see) transmission cooler hoses, thermostat, timing belt, water pump, oil pan is dented and may be weeping (or maybe that's PS fluid), engine mounts... The "while in you're in there"s are starting to add up.
PS pump might be good, just old hoses get brittle. I took my PS out and changed the 3 O-rings ( search in Sticky) My PS pump was all gunked up from seepage, but it didn't actually drip on alternator. Cleaning takes the longest, I think only the car owner would spend so much time and effort into cleaning
I think this might be a worthwhile investment. Pump not making any noise but steering is heavy and definitely leaking. There's also a leak on the driver side of the oil pan. I think that's the return line that runs around the front of the oil pan?
The timing belt and water pump were done at a Lexus dealership at 97k miles (now at 142k). However, that was more than 15 years ago in June of "06 (45k miles in more than 15 yrs?? I have my suspicions about the odometer). The LS400 has a belt and regardless of mileage I think I'll do it while I have it apart due to age. Also noticed what I believe to be power steering fluid all over the place now that I have it up and the under cover off and getting up close and personal with it. So, let's see.... radiator hoses, radiator, power steering (pump? lines? we'll see) transmission cooler hoses, thermostat, timing belt, water pump, oil pan is dented and may be weeping (or maybe that's PS fluid), engine mounts... The "while in you're in there"s are starting to add up.
Wow. When it rains, it pours. These are all maintenance items that are all coming together at once. Maybe a blessing in disguise. No damage to any major components. You'll be doing it all while you've got things apart. It's a terrific car that should give you plenty of luxury driving for a long time to come and no car payments!!
Wow. When it rains, it pours. These are all maintenance items that are all coming together at once. Maybe a blessing in disguise. No damage to any major components. You'll be doing it all while you've got things apart. It's a terrific car that should give you plenty of luxury driving for a long time to come and no car payments!!
That's good that you are getting to these before any major issues come into the process. It hurts the wallet yet once you've done the maintenance you should be good.
The timing belt and water pump were done at a Lexus dealership at 97k miles (now at 142k). However, that was more than 15 years ago in June of "06 (45k miles in more than 15 yrs?? I have my suspicions about the odometer). The LS400 has a belt and regardless of mileage I think I'll do it while I have it apart due to age. Also noticed what I believe to be power steering fluid all over the place now that I have it up and the under cover off and getting up close and personal with it. So, let's see.... radiator hoses, radiator, power steering (pump? lines? we'll see) transmission cooler hoses, thermostat, timing belt, water pump, oil pan is dented and may be weeping (or maybe that's PS fluid), engine mounts... The "while in you're in there"s are starting to add up.
I would consider the PS issues a separate job if you are doing a timing belt service. Many parts can be easily replaced "while you're there" but PS pumps on these cars are notorious for continued headaches.
Rebuilding it with the seal kit mentioned above is a good idea but it could also be the ACV on the bottom of the pump. In a nutshell, don't expect the PS issue to be resolved on the first try...
Thanks for this ^^. I had a shop check out the car and they came up with a laundry list of things that needed done. One of them was replacing the PS pump. The quote for this was spendy so I started doing research. Since the pump is making no odd noise even at full lock I had wondered whether the ACV could be the culprit. For the price versus a new pump I think it's worth a shot. Could this valve be the source of a fluid leak? Steering is heavy when moving slow, fine at speed. After having a good look there is definitely PS fluid leaking from somewhere - I need to clean everything up real well and figure out where the leak is coming from.
I'm imagining all of this stuff is going to be easier to get at while I have the radiator out to replace due to the coolant leak. Timing belt because it's 15 years old. Probably not necessary to take the radiator out to work on the PS pump, lines, etc... but wouldn't there be more room to work with it out?
Thanks for this ^^. I had a shop check out the car and they came up with a laundry list of things that needed done. One of them was replacing the PS pump. The quote for this was spendy so I started doing research. Since the pump is making no odd noise even at full lock I had wondered whether the ACV could be the culprit. For the price versus a new pump I think it's worth a shot. Could this valve be the source of a fluid leak? Steering is heavy when moving slow, fine at speed. After having a good look there is definitely PS fluid leaking from somewhere - I need to clean everything up real well and figure out where the leak is coming from.
I'm imagining all of this stuff is going to be easier to get at while I have the radiator out to replace due to the coolant leak. Timing belt because it's 15 years old. Probably not necessary to take the radiator out to work on the PS pump, lines, etc... but wouldn't there be more room to work with it out?
I have a 91 Ls. Had the same PS problem as they all do. It jerked slightly when I turned and there was a leak. Mech. said 4K for steering rack. I said Lucas oil, it's been turning flawlessly for 5 years now. Occasionally it drops a bit of fluid, I add approx. 6 tablespoons again and it's good for an entire season.
Now, I've run into a coolant leak with the added bonus of no interior heat (thank-you) -10 Cel. here in Waterloo, Ontario. (air in the system) So many variables. Firewall hoses are good, rad hoses good. Overflow on a 91 is the only access to adding removing fluid other than disconnecting hoses. Has a rad cap on the overflow (never seen it done that way before). Going to follow this thread to see if any more clues come up.
Heat display sits at half (normal, but rises too fast) then the fans kick in and it's stable. I want to keep this car, but it's 29 years old and I can't rebuild it. Two rust spots, clean underbody. Amazing beast, but it may have to go soon.
I have a 91 Ls. Had the same PS problem as they all do. It jerked slightly when I turned and there was a leak. Mech. said 4K for steering rack. I said Lucas oil, it's been turning flawlessly for 5 years now. Occasionally it drops a bit of fluid, I add approx. 6 tablespoons again and it's good for an entire season.
Now, I've run into a coolant leak with the added bonus of no interior heat (thank-you) -10 Cel. here in Waterloo, Ontario. (air in the system) So many variables. Firewall hoses are good, rad hoses good. Overflow on a 91 is the only access to adding removing fluid other than disconnecting hoses. Has a rad cap on the overflow (never seen it done that way before). Going to follow this thread to see if any more clues come up.
Heat display sits at half (normal, but rises too fast) then the fans kick in and it's stable. I want to keep this car, but it's 29 years old and I can't rebuild it. Two rust spots, clean underbody. Amazing beast, but it may have to go soon.
"Has a rad cap on the overflow (never seen it done that way before)."
The pic correctly shows the official screw for filling and bleeding the cooling system. But you don't actually *need* to ever touch it. On my '91, for the longest time it would leak a little there. When I finally tuned it up enough and got the proper sealing washer, the leak stopped, and I never touched it again.
I add through the overflow tank, whether topping it up or filling it from empty. Never ever opening that screw on the thermostat housing, since I don't want to risk creating another chronic leak.
The Lexus overflow tank design is different from many, but certainly not unique. Both my BMW and Porsche are similar. The tank is directly connected to the rest of the cooling system at all times, seeing system pressure, with coolant free to flow in/out of the tank at all times. If the pressure limit set by the cap is ever exceeded (should never happen under normal conditions), the radiator cap opens to relieve pressure, allowing coolant / vapor to exit through that black tube, routed through to empty under the car. After driving, as the coolant and engine cool down, a small amount of air can be sucked back in through that radiator cap to equalize pressure. This way, the cooling system should be completely isolated from the atmosphere at all times, as long as the pressure remains within spec.
More common coolant systems simply have a radiator cap on the radiator, exhausting to a vented (always at atmospheric pressure) overflow tank if pressure is exceeded (and in these systems, this is completely normal, due to thermal expansion of the coolant, and no air gap to accommodate the increase in volume), and suctioning the coolant back into the radiator as it cools.
So on the Lexus system, it should be just fine to fill through the overflow tank. But on the other basic type, filling through the overflow tank may help in "topping up" but will not work at all for major filling. In those cases, you'd need to fill through the radiator cap into the radiator.
"Has a rad cap on the overflow (never seen it done that way before)."
The pic correctly shows the official screw for filling and bleeding the cooling system. But you don't actually *need* to ever touch it. On my '91, for the longest time it would leak a little there. When I finally tuned it up enough and got the proper sealing washer, the leak stopped, and I never touched it again.
I add through the overflow tank, whether topping it up or filling it from empty. Never ever opening that screw on the thermostat housing, since I don't want to risk creating another chronic leak.
The Lexus overflow tank design is different from many, but certainly not unique. Both my BMW and Porsche are similar. The tank is directly connected to the rest of the cooling system at all times, seeing system pressure, with coolant free to flow in/out of the tank at all times. If the pressure limit set by the cap is ever exceeded (should never happen under normal conditions), the radiator cap opens to relieve pressure, allowing coolant / vapor to exit through that black tube, routed through to empty under the car. After driving, as the coolant and engine cool down, a small amount of air can be sucked back in through that radiator cap to equalize pressure. This way, the cooling system should be completely isolated from the atmosphere at all times, as long as the pressure remains within spec.
More common coolant systems simply have a radiator cap on the radiator, exhausting to a vented (always at atmospheric pressure) overflow tank if pressure is exceeded (and in these systems, this is completely normal, due to thermal expansion of the coolant, and no air gap to accommodate the increase in volume), and suctioning the coolant back into the radiator as it cools.
So on the Lexus system, it should be just fine to fill through the overflow tank. But on the other basic type, filling through the overflow tank may help in "topping up" but will not work at all for major filling. In those cases, you'd need to fill through the radiator cap into the radiator.
Thank-you. While I'm in there, I might as well also check out the screw for filling and bleeding to see if the sealing washer is still good. Others were saying if the thermostat is toast there may be coolant leak coming from underneath because of it.
An unrelated side note - last week, parked my 91 black onyx at Bridgeport plaza Waterloo, came out an another gold 1st generation is parked right beside it. The chances of even seeing those two together in same city is rare. Plenty of parking spots, but chose to park beside mine...other owner was having a little fun. His was in great shape, no rust, tinted rear windows. Another tank lives on!
01-16-20, 01:00 PM
