2004 Sequoia- Small coolant leak

Hi everyone,
2004 Sequoia with 260K. I recently went through an issue back in August with my timing belt tensioner breaking clean off and the motor skipping timing. The mechanic threw the tensioner back on and she's purring like a kitten.

Fast forward to today, truck runs great but I have a small coolant puddle under my truck, i cant completely see where its leaking from but it appears to be where the aluminum block meets the steel? I also checked under the oil cap and it appears to have a milky residue. Do all signs point to the head gasket? If so, what can I expect for cost on that job? Dip stick oil does not look milky. Do i dare continue to drive it? What would you do?

 

The milky residue isn’t something to be worried about. It’s typically condensation from the engine and shows up if you’re in the habit of doing short drives before the engine comes up to temperature. When it’s bad, it looks like thick mayonnaise. I’ve been there plenty of times myself.

I’d probably try to gauge how bad it’s leaking and keep an eye on your thermostat gauge until you can get it fixed. If it’s leaking pretty bad, I probably would drive only short distances around town and periodically checking on the coolant level in the radiator when cool and add more if appropriate.

 

Wow, you're a lucky dog. Go buy a lottery ticket!
(and if you win, please don't forget about me!)

Like Bill said, milky under oil cap is from short-trip driving, it's purely condensate in the cap caused by lack of getting the engine up to temp, or extra-rapid cooldown. That said, if you're doing the kind of short-trip driving that causes that, that's really frickin' hard on your engine, and you need to make sure you're doing oil changes based in time versus miles. i.e. those oil changes should be every 3,500-4,500 miles and no more than every 12 months. Don't care what kind of oil you use or what it says, short-trip driving is harder on oil and your engine and requires reduced maintenance intervals.

Beyond that, I'm worried - especially if you're not doing your own maintenance - your mechanic is shorting you on maintenance. You should be replacing the following items every 100k miles (or 10yrs, or half that if you use non-OEM parts):

• Timing belt
• Tensioner
• Water pump
• Related pulleys
• Water pump-related gaskets

Those things all comes in a convenient OEM kit from Aisin. It sounds like someone failed to do so, OR they used non-OEM parts (i.e. not Aisin, purchased from a reputable outlet or direct from Toyota). That failure could have royally fucked you just now, your V8 is a low-interference engine, and timing belt failure or major time issues can boat anchor that thing. So I guess the unsolicited advice I'm offering is, while I'm sure you're potentially happy with your mechanic, I'd be pretty pissed right now that something as simple as a tensioner hasn't been replaced. I hope they're at least doing the other stuff (pulleys, water pump, timing belt) at the same time, and not waiting for catastrophic failure that leaves you without an SUV anymore.

Last, "what would I do, how much will it cost?"

Well, given there's about 10 common things that can leak coolant on these trucks, some pretty severe (water pump, and given the tensioner failure, I'd be worried that hasn't been done...), and others are simple. Water pump is gonna cost you $$$ if you don't do it yourself. Something like the thermostat housing or a hose is something you can do in your driveway for pennies on the dollar.

This thread covers common issues with these trucks and links to solutions, including good info from the "recalls/annoyances' section:

• Coolant leaks: Three common causes: One is the is the gasket behind the thermostat housing, another is the coolant crossover at the rear of the block, and last but not least, old radiators is another source. Here's a list of things to check if you're losing coolant. For repairing the leak behind the t-stat housing, check this out. For the coolant crossover tube issue, you'll likely find coolant at back of the block, near where the trans and engine meet, check this reply for video/fix. This post is for leaks at t-stat housing/inlet neck. This reply contains links to three other off-brand/odbball leak cases. For radiator leaks, this is one example of a tiny one - always replace with Denso brand radiator, and know different cab types use different sizes, careful where you order, scAmazon especially tends to deliver damaged products often (RockAuto has a spotless record with forum members). Proactive radiator replacement is wise. The transmission line routes through the bottom of the radiator ... go look up "pink milkshake", it happens in these trucks.

You really need to use your eyes, and follow the pink crust (your Sequoia should be using the proper pink long-life coolant) and trace it back to the source. Take a picture for us. One of us can probably tell you what it is. There's only so many gaskets and joints in the cooling system...

NOTE: It's normal to have a little pink crust buildup around hoses, joints, and some parts even have weep holes where you'll see some coolant crust-puddling happen. This is normal. Take some pics, use the 'upload a file' button on the text reply area to put them in replies here.

But seriously, the bigger takeaways here are:

1. It's possible your mechanic is screwing you over by not doing basic steps that cost near-nothing and should be part of routine maintenance.
2. It's important to understand, when people (or your Toyota Owners Manual/Maintenance guide) give you a specific lifespan on a part, that number only applies to using authentic OEM parts -- you will get far less mileage with aftermarket parts, along with a higher failure rate.
3. Don't be afraid to poke your head around inside the engine bay of your truck, looking for oil leaks, coolant leaks, grease slinging, etc.
4. Know the big killers of 1st gen Sequoia/Tundra:
   1. Lower ball joints: Replace proactively at 100k-125k miles. NEVER use non-OEM lower ball joints, always replace your hardware with fresh hardware each swap ... there's a thread with hundreds of pictures of totaled/fucked up victims who failed to listen to this, and installed Moog, NAPA, or other.
   2. Radiator: Replace proactively with your timing belt/water pump service. The transmission pass-thru at the bottom of the radiator gets fitting rot and will send coolant into your transmission, and ATF into your engine.
   3. Timing belt/water pump/tensioner/pulleys: Replace at 100k or 10yrs. If any of these items fail on the V8 engine in our vehicles, there's a 50/50 chance your engine is toast should the timing jump. If you're over 1,000-1,500 RPM and it jumps or loses time, that's more like 80% chance.
   4. Rust: Frame rust is a huge issue, that thread I linked above with 'common issues' gives you where to check.

Anyone who is unaware of the above well-known issues with our trucks or who tells you those big-ticket items are "hype" or "bullshit" should not be working on your vehicle if you want it to make it to 400k, 500k, 800k miles. We have ample evidence on this forum alone, but Facebook groups are littered with even more.

 

Just a comment on the above. Something I've noticed while I've been searching FB Marketplace for running boards for my newly acquired Gen 1.
SO MANY of the pictures of the Gen 1's being parted out are missing just one front wheel. That missing wheel is often shown in another picture laying in the bed of the truck, so it hasn't been purchased. I'm guessing a significant number of those had the LBJ go on those vehicles. They also thought it could not happen to them.

I was going to do my LBJ last weekend, but it rained non-stop. 2 and 3 are done already (last week) and it's very clean frame wise. I'm off Friday, so doing the LBJ's then!

 

Thanks for the info! WOW!

Couple details on the belt tensioner: I had the timing belt replaced 4/2023 and the tensioner breaking off happened on a road trip where i was forced to use the local mechanic on 8/2024.

I'll try and get some pics, of course it's not leaking any where that I can see at the moment. The mechanic that installed the new tensioner also had to put in a new radiator due to breakage during removal.

Thank you again for all the knowledge!

 

When it dips down to freezing my truck weeps a bit of coolant from the hoses that go to the oil cooler.

 

That shouldn’t be happening. Mine is dry as a bone in freezing temps.

 

Yea, i have the hoses to fix it, but by the time it warms up enough to get at it, its dry...maybe this winter i'll get it done.