Doc Yota

Hello all.... what can cause a coolant leak when I fill through the filler bolt on the motor with the car off?

I am in the process of tracing a coolant leak in my(99 LS400) system. I have checked all of the simple things(upper and lower hoses, radiator, new reservoir cap,t-stat housing) and all are fine. I then decide to top off the system with dye through the fill bolt on the motor with the car off. With plenty of coolant still in the system I noticed that water would leak out as soon as I pour it in the filler hole. The leak is intermittent and appears at the front of the motor between the a/c compressor and the oil filter and only happens while the car is running and just a few moments after I turn it off. The car has never run hot and I hear no signs of water pump bearing issues. My Timing Belt and Water Pump were replaced at 70K miles and I now have 150K. Could my problem be the Water Pump, or the water inlet housing? Has anyone ever experienced this problem? Love this car. I have never had any major issues with this car since I bought it 5 years ago. PLEASE HELP.

timmy0tool

iTrader: (7)

i hope it is not your water pump gasket, which is likely if not properly installed. it could also be your water inlet since it needs to be sealed with gasket material when re-installed.

radiator cracks do develop especially at the plastic endtanks, and could be hard to pinpoint but you said the leak is coming from the engine side.

steve2006

If the engine has the same as earlier LS400s there are 2 engine block coolant drain valves one of which is located in the area you mention, you will need to get under the car and take a look to see if it has broken or leaking.

The link below shows the locations.
http://www.lexls.com/tutorials/cooling/coolant.html

Sewpra

I agree with Steve, that area is exactly where that engine block drain is and it's kind of deep in there, without a long extension for my 3/8 I needed to throw an angled socket on as well for extra length.

I don't see how any other leak could make its way to that area and I'm sure the water jacket seal is on the passenger side with the 99s also.

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Doc Yota

Thanks guys. I appreciate your response. To give an update, I went to top off the reservoir with the car cold and the engine fill bolt in place and it started leaking from the same spot. What puzzles me is the reservoir was more than half full and the block was full as well. Why would the system not leak when there is plenty of coolant in the system but then leak when I try to fill though the reservoir or the fill bolt? Is there a hose I'm missing somewhere? I will keep searching. I would hate to take it to Park Place if its something simple, If anyone can think of anything else please feel free to reply.....Thanks in advance.

Doc Yota

Correct the engine side is the problem. If the water pump gasket is bad wouldn't it leak all the time?

randal

Leaks are hard to pinpoint at times, especially without pulling some of the front components.

Now, I would like to give you something to ponder...since you have 80k miles on your existing pump and belt AND you have a troubling leak, would you not consider just having a new pump and belt installed?

The belt is due in just another 10k miles and given your current situation, it would seem wise to me to bite the cost bullet and have those items replaced. With the front part of the engine disassembled, you will find the culprit and have a new pump/belt for peace of mind.

Sewpra

Agree with Randall, but those leak characteristics are kind of odd, if its a very small leak like almost a small drip maybe the car running or the topping off of the fluid changes the gravitational pressure just enough to agitate the leak, it would certainly make sense that maybe that drain block is just ever so loose.

Otherwise maybe it is a hose problem like you say. Since the reservoir tank is on the passenger side in that generation I would look up the location of any bypass hoses or anything like that on there, but I still would check the drain bolt first on the block.

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sha4000

iTrader: (1)

Can you take a pic and upload it? That always helps when trying to diagnose problems. Like they said the only thing by the oil filter is the drain **** and if you jacked up the car on that side I'm pretty sure you can see if that's where the leak is coming from.

Doc Yota

Sha, I will try to take a pic but its nice and dark here so it may be the morning before I can get a good one. Randal makes a good point. Its approaching time to change the Water Pump again. I did it early last time might as well do it early this time. I was in the process of putting it up for the summer and driving my LS430 and my Del Sol with the top out mostly. I just wanted to get it drive ready for the fall. Hope you understand, I'm not cheap, I just paid $1300 on the timing belt and waterpump on my LS430 just a few weeks ago. Did not anticipate having to do that job on my LS400 for another year. Thanks guys....I'll post pics tomorrow.

sha4000

iTrader: (1)

We understand that all repairs are done when the funds are available and no one thinks your cheap.

Doc Yota

I hope you guys read this because I cant believe it...

I went for a drive today expecting the leak to continue. Out for 20 minutes I get home....no puddle under the car. I decide to push my luck and drove it to Olive Garden with my wife for our anniversary. Not far from home but far enough to make the leak appear....no leak. I have bleed the system got a new cap and changed to hoses that connect to the black resonator connected to the intake since I had to crown removed(they were badly cracked). Everything I mentioned was done before my original post (except the resonator hose repair) and it continued to leak until today. Over the years my reservoir level would drop to the low line maybe a few times a year and I would top it off with water only because I knew the mixture was correct after my TB/WP was replaced in 2009. Could the water to coolant ratio have been so far out of whack that it made the system "purge"? Have any of you guys ever heard of this happening? Or did an angel come down from heaven and stop this leak, because the system is completely full and now its not leaking a drop in 100 degree Texas weather with the a/c blowing driving around for hours, sitting still in parking lots and my driveway running....I've tried it all and the leak just vanished.

randal

Doc, if you have lived a clean life, then yes, maybe an angel did take away the leak.:-)

Either you mistakenly thought there was a leak or, more probable, the leak is intermittent. And will be back. They do not miraculously heal unless you put stop leak in there.

Doc Yota

I was not mistaken I have two witnesses that saw the leak and know it was a coolant leak. Maybe it will return. If it does I will continue the mission. I don't believe that leaks just disappear but this one stopped with no stop leak. Stop leak will never touch my hands let alone my cars...forget about it. Just wanted to see if anyone has heard of the system purging itself if too much water is mixed in with the coolant.

randal

Too much water lowers the boiling point and *could* result in excess boiling and loss. So, I suppose it is possible, though not probable Keep an eye on it and start saving for a timing belt/water pump service.