Coolant Loss - no obvious visible leaks. Any tips?

[abuck99]

Hard to tell what that is- better if you clean that area and watch.

But check your coolant 1st thing in the morning- under the cap as explained above.

Are you clear on how to check for coolant leaking under the crank pulley- to rule that out?

 

[1150A]

Hard to tell what that is- better if you clean that area and watch.

But check your coolant 1st thing in the morning- under the cap as explained above.

Are you clear on how to check for coolant leaking under the crank pulley- to rule that out?

Got it - will clean it and check it tomorrow as well as the coolant level in relation to cap - will update.

No to be quite honest I'm not familiar with where the crank pulley is. Researching that now but if you had any tips that would be super helpful!

 

[abuck99]

Courtesy of @2001LC

Under harmonic balancer area

There’s a small narrow opening below and behind the harmonic balancer pulley

Couple of good leak threads - gives you some places to inspect.

Coolant leak at water inlet and..

I may stop using Hydens based on your observation. But true OEM for $35 sound to good. Have you any picture of bearing you can share? I put a Hyden idler pulley on The King just as a test, but only have a few thousand miles on it. I recently heard some noise and ended up replacing fan clutch...

forum.ih8mud.com

Coolant Leak, Drip Coming Down Behind Crankshaft Pully

I replaced the timing belt and water pump about six months ago (7000 miles), it was fine until lately I started smelling coolant and checked in under the hood I notice a drip behind the crankshaft pulley coming from what I believe is the water pump area. I know I may need to open up the tc...

forum.ih8mud.com

 

[willmtaylor]

When I couldn’t find an obvious leak a few weeks back, it was seeping out from beneath the thermostat housing area.

Do make sure to clean off whole area as much as possible though when looking for fresh leaks.

 

[Mike NXP]

Got it - will clean it and check it tomorrow as well as the coolant level in relation to cap - will update.

No to be quite honest I'm not familiar with where the crank pulley is. Researching that now but if you had any tips that would be super helpful!

Yep, gotta clean everything or else you will be constantly guessing, especially on small leaks. Lots of threads on here about chasing leaks while staring into a dirty nasty engine bay.

Maybe post a few more pics?


Are you handy enough to drop the skid plate down below? I think there are like 8 bolts holding it on. Getting a view from the bottom up may help a lot for diagnosis and cleaning.

I don't think it's your head gasket, don't waste your time pulling and smelling your plugs. Probably just a small leak somewhere

** Make sure you check coolant level in radiator and reservoir to be full and within spec. Check with engine fully cooled down.

 

[1150A]

Got the radiator cap finally and do still smell it for sure. Today I was finally able to take it on a longer-ish drive and I was able to pinpoint a leak. I still can't tell exactly where it's coming from but looking at the photo abuck99 posted, I believe it's under the harmonic balancer. I can't see exactly where it's coming from but do see the drips down there as you see here.

Will pull off cover and update tmrw.

 

[1150A]

If it’s the water pump, and it could be, then you should see it coming out of the bottom of the crank cover on the crank shaft. I have used the AISIN kit on both of my 100’s, but unless you really know what you are doing - it is simple to miss a bolt or miss a torque setting.

I’d suggest pulling all the covers under the vehicle, getting it hot, and looking for leaks. The leak should be obvious given the amount of coolant loss if it hot.

My 2 cents, but if you can smell it - it’s in the engine compartment.

Hard to tell what that is- better if you clean that area and watch.

But check your coolant 1st thing in the morning- under the cap as explained above.

Are you clear on how to check for coolant leaking under the crank pulley- to rule that out?

Thanks @abuck99 and @LWA55DAL - super helpful.

Pulled cover off finally and went for a short drive. It didn't leak quite as much as yesterday but I do see a little more clearly where it's coming from. Still need to do some research here with all the threads you guys shared but sounds like things are leading towards water pump? (red arrows are coolant traces, yellow arrows are maybe coolant?)

 

[abuck99]

Can’t really tell from photos but if you think coolant is leaking down on tensioner from above - I suspect the underside of the thermostat housing area.

If it were water pump I think you’d first see it leaking from the weep hole and it looks dry in this picture.

If when that last time the job was done, a new gasket wasn’t used for thermostat- it can leak there. Or where the thermostat inlet housing meets the engine- if wrong sealant used or poor prep work, it will leak. I would look closely there.

Sounds like you’re getting close.

FYI water pump is behind fan bracket- you won’t be able to see it

 

[1150A]

Can’t really tell from photos but if you think coolant is leaking down on tensioner from above - I suspect the underside of the thermostat housing area. If when that last job was done, a new gasket wasn’t used for thermostat- it can leak there. Or where the housing meets the engine- if wrong sealant used or poor prep work, it will leak.

Sounds like you’re getting close.

Thanks! I did check my receipts from last job and it does indeed say thermostat w/ seal was replaced. The more I stare at it, I feel like it may be coming from that tube thing since there's residue dripping down it and that's just about where its dropping down on the cover. Stupid Q - but what is that part called?

Also - I'm not sure if mechanics are trying to sell me on it, but I am told to replace timing belt if coolant spilled all over it. While I don't see any residue on it from first look, I can't say for sure. Would you also agree on that? If I need to do a tbelt job again, I'd do it thru a shop anyways so I figure I may as well bite the bullet and pony up the $$ now.

 

[Bisho]

Thanks! I did check my receipts from last job and it does indeed say thermostat w/ seal was replaced. The more I stare at it, I feel like it may be coming from that tube thing since there's residue dripping down it and that's just about where its dropping down on the cover. Stupid Q - but what is that part called?
View attachment 3303372

Also - I'm not sure if mechanics are trying to sell me on it, but I am told to replace timing belt if coolant spilled all over it. While I don't see any residue on it from first look, I can't say for sure. Would you also agree on that? If I need to do a tbelt job again, I'd do it thru a shop anyways so I figure I may as well bite the bullet and pony up the $$ now.

That is the timing belt tensioner. Any fluid on it is coming from somewhere else.

 

[2001LC]

Thanks @abuck99 and @LWA55DAL - super helpful.

Pulled cover off finally and went for a short drive. It didn't leak quite as much as yesterday but I do see a little more clearly where it's coming from. Still need to do some research here with all the threads you guys shared but sounds like things are leading towards water pump? (red arrows are coolant traces, yellow arrows are maybe coolant?)

View attachment 3303217

View attachment 3303218

View attachment 3303219

Seeing green coolant, speaks to shop you're using. Not good IMHO! One of the benefits of Toyota red coolant (LL). It leaves a dry crusts bubbly pinkish glob at leak, making finding easier.

Work your way up, from green coolant drips. Focus on:
Water inlet, where it's FIPG seals it to water pump, where it's O-ring seal to water bypass front, where hose connects to it, it's cap (thermostat housing lower hose connects to). Also front water bypass, water gauge sensor threaded into it. Also hose(s) connected to throttle body.

This is picture, from a 06-07 VVT. Which water bypass and inlet are similar to the 98-02

Water bypass & water inlet

 

[1150A]

Seeing green coolant, speaks to shop you're using. Not good IMHO! One of the benefits of Toyota red coolant (LL). It leaves a dry crusts bubbly pinkish glob at leak, making finding easier.

Work your way up, from green coolant drips. Focus on:
Water inlet, where it's FIPG seals it to water pump, where it's O-ring seal to water bypass front, where hose connects to it, it's cap (thermostat housing lower hose connects to). Also front water bypass, water gauge sensor threaded into it. Also hose(s) connected to throttle body.

View attachment 3303656

Thanks @2001LC - I keep trying to find a drip from the circled areas that you posted but I am finding it's dry all dry in those areas. No wetness at all.

I keep looking for a trace above the timing belt tensioner but it seems everything is below it. With that said, I can now see some wetness around the weep hole on harmonic balancer. The odd thing is I don't see anything below or around that. Everything else is to the side of it near the timing belt tensioner.

Any ideas here?

 

[2001LC]

Finding coolant at front weep hole, is typically Water pump. Which @abuck99 pointed out in picture above. But be sure not from above WP, before replacing water pump..

Some of those top side leaks, can be hard to spot. It helps to pull engine cover and air pipe. Use flash light, mirror and camera to see under and around water inlet, also top of water pump gasket. If still nothing found. You can pull upper RH timing cover easier than LH. I've a guild able bore-scope, I can snake around WP. Which I could also pull cam sensor wires' grommet, and snake into LH cover. Many shop have bore-scope.

Also I'll note not all Aisin kits are equal (China made boot leg) and even a real Aisin water pump can fail.


Area under inlet O-ring (yellow circle) is hard to see until air pipe off. You can see into timing belt area LH cover off, but not well without a borescope.

Under inlets FIPG seal (rectangular area circled in yellow) is hard to see. A leak here can get behind plastic t-belt cover, and come out lower weep hole.
The rubber cam grommet (circled in red) removed. Makes for fast borescope point of entry.

 

[1150A]

Getting antsy and took it to the Toyota dealership for diagnosis.

They say 90% sure it’s the head gasket. They recommend taking R. timing cover to do the inspection.

Bummer

 

[abuck99]

Who at the dealership told you that- service writer guessing or did they perform some testing and then provide you with results pointing to HG?

You’re a captive audience to them and they’ll try and sell you an expensive job- so beware.

But you’ve already done a system pressure test as referenced in post #1 - nothing negative from that right? And none of the typical indicators of HG leak as you referenced. You could remove spark plugs, borescope inspect each cylinder and easily tell if HG leaking.

Noob mechanic-your opportunity for practice and learning is before you- did you follow @2001LC advice in the previous post (picture heavy) to look at coolant inlet, bypass area? If ruled that out I’d pull the radiator out, fan, alt, basically like doing a TB service and remove all of the covers- inspect the components you can’t see- water pump, idler (it’s mounting bolt known to leak if not sealed during service) etc. while the rad is out- maybe take it to a radiator shop and have it pressure tested again.

 

[2001LC]

Head gasket leaks I've seen. Have been along length of head. We've heard, but I've doubted, head gasket leaks without overheating warping head. When head gets warped, this would almost certainly be along length. These leaks are almost always visible, without removing any more than under shield and engine cover. So the shops you've had looking, should have spotted. They also are under intake manifold or sides of block. Not in front of engine.

But let's assume a fluke, and head gasket leaking at front end. If head gasket at front BK2, it be easy to confirm. First by looking here (pink circle). Can be seen easily with air pipe off and a flash light. Also from below with #1 under shield (Skid #1) off.

Second, by removing BK2 upper plastic timing cover. Red arrow is pointing to head gasket. I would want leak confirmed, before removing a head.
Again using a borescope, they can pin point and provide pictures of point of leak.

Front AND Rear Water bypass, attaches to heads at yellow circles. Water pump port for water cross over pipe goes into back of water pump (SM O-ring sealed) blue circle.
If at BK2 front Water bypass gasket (yellow), It would be seen on top front of head. SM O-ring would leak into engine valley. They "may" also flow down front of engine BK2 side.

The most difficult would be the water pump leak, but can be done with bore scope.

Water pump leaks, not at water inlet FIPG seal (rectangle port water inlet attaches to) or small O-ring port of water cross over pipe on back side. But actually from a water pump failure. Are most often found at of two points. First being on LH side (BK1), where there is a weep hole in water pump. Which should first show-up on BK1, just below upper timing cover. Than weep at lower timing cover. This weep hole comes from shaft of water pump. When water pumps fail, bushing in shaft goes bad, and leaks at weep hole first. Then once really bad, at drive shaft of water pump leaks.

WP weep holes (on BK1) often, have some sign of weepage as seen here.

 

[2001LC]

Some head gasket leaks I've seen along length of head, inner and outer sides.

 

[2001LC]

Front of block at water pump gasket BK2. Is a spot that could developed leak.

Red circle is on, BK2 side of water pump. Air hole (Weep) on on BK1

Red circle is BK2 water pump gasket side. But also notice yellow circles. The large is water bypass to water inlet port sealed with large O-ring. I see FIPG used here (wrongly so) which it should not be. Which often results in leaks. This too would show-up on front BK2 side of engine. The next medium size yellow, is small O-ring of water cross over pipe, going into back of water pump. This may leak down front of BK2.. Next is a small water tube on throttle body. Leak hear may would flow down front of engine.

Additionally water inlet has hose attached coming up from oil cooler water pipe. It's more to center of engine. But it, as any water inlet leak, may flow down BK2

 

[1150A]

Thanks guys ton of info here and a lot of my head but hoping I can figure it out.

Yes I was a little hesitant on what they said too but had a little more trust being that I went to dealership this time.

FYI: exact notes are: Inspected coolant leak on arrival. Found coolant on t-belt tensioner. Pressure tested, no leak detected. Let vehicle run on lift and verified leak from r. side cylinder head gasket. Rec removing r. side timing cover for further evaluation.

Do keep in mind they called me about 25 minutes later after I dropped off the car to ask to send photos of the leak (I'm guessing after they pressure tested w/ no leakage).

Question @abuck99 - rather than pulling plugs, would doing oil change be sure way to tell if HG is leaking?

I do still have to check the bypass area. Still confusing to me with the pics but hoping to figure that out today.

 

[abuck99]

Thanks guys ton of info here and a lot of my head but hoping I can figure it out.

Yes I was a little hesitant on what they said too but had a little more trust being that I went to dealership this time.

FYI: exact notes are: Inspected coolant leak on arrival. Found coolant on t-belt tensioner. Pressure tested, no leak detected. Let vehicle run on lift and verified leak from r. side cylinder head gasket. Rec removing r. side timing cover for further evaluation.

Do keep in mind they called me about 25 minutes later after I dropped off the car to ask to send photos of the leak (I'm guessing after they pressure tested w/ no leakage).

Question @abuck99 - rather than pulling plugs, would doing oil change be sure way to tell if HG is leaking?

I do still have to check the bypass area. Still confusing to me with the pics but hoping to figure that out today.

You can look at dipstick and check for moisture in oil , looking under oil filler cap for milky residue. Drain oil and send for analysis is another option.

So I’m not clear on your statement about dealer calling for pictures- they wanted your pictures or they sent you pictures? How did they determine coolant on TB tensioner- only from your pictures or their investigation. Did they even put your truck on a lift and have a look?

Before doing any dealer prompted service do your homework as offered by @2001LC and rule out those items. It’s quite easy work- get a copy of FSM study and proceed. Or go pay for it to be done-