engine coolant leak help

[tootsie]

I thought i had a head gasket leak or a cracked head on a 1997 4runner so proceeded to tear into the engine. Upon getting the heads off, I did find a crack in the 3rd cylinder between the valves but not sure if that wouldve caused coolant to leak. The pistons also looked mostly normal -- maybe a tiny bit cleaner. The head gasket also seemed okay besides a little rusty area.

I did notice coolant sort of pooling around the engine coolant bypass pipe in the valley. Would this have caused coolant leak -- main symptoms were white smoke blowing out of tailpipe?

Just unsure how to proceed with this repair -- maybe getting a new head and gasket and replacing that pipe or redoing the gasket beneath the pipe? or new engine?

 

[Malcolm99]

how much coolant where you loosing, did you look in the cylinder for coolant or evidence of steam cleaned cylinder before removal of both heads?, compression or leak down test?, did the exhaust gases smell sweet like rad fluid, white smoke could also be cooler weather, was it hydro locking while sitting?. The coolant bypass pipe is defiantly leaking externally, I think it is a o-ring sealing it to the block. I would have identified the location of the leak before disassembly as it may not be a head gasket, or only one head gasket typically, was it overheated at any point.

 

[tootsie]

maybe 1/4 cup over a week or two. and unfortunately no didnt look in cylinder or do any of those tests and probably should of but didnt have the tools -- sort of did this based on sweet smelling tail pipe white smoke during any time of day and folks around me were saying that that was definitely a cracked head or head gasket so just went for it. i am curious what else could it be if not for that? and i dont think it ever overheated at anypoint.

 

[2TH4IST]

Hmm looks pretty normal. Replace the cracked head. The coolant leak looks like it was from the lower intake plenum gasket failure (between the head and intake manifold. They like to rust out the stock gaskets there. That's how the rear intake studs get all messed up from.

 

[JWaldz]

The 3.4 engines are resilient. It took around 2 years after head failure (cylinder 3) with off and on symptoms for my engine to finally go.

Even a tiny crack with a failing headgasket can cause a leak. Without deep diving, simply put, the amount of compression the engines are under tend to find any weak points and exploit them.

The sweet smelling white exhaust is coolant getting into your combustion chambers and burning off. Clear indication of a failure somewhere and NO GOOD for engine components.

If you can, get the head decked (resurfaced), clean everything up, replace the headgasket, maybe replace a couple worn looking components, and let her ride. You might need a new engine eventually, but this buys you some time.

 

[phattyduck]

I'd be suspect of a head gasket issue on the rear cylinder on the passenger side (I think that's 5?). But yes, it also looks like you had a leak in the lower plenum and an o-ring leak on the front end of the coolant bypass pipe.

You can see the neglected cooling system from the rust in there... Looks like the PO didn't like coolant changes. I do see you were using Red/Pink most recently, which will be good going forward.

-Charlie

 

[tootsie]

Hmm looks pretty normal. Replace the cracked head. The coolant leak looks like it was from the lower intake plenum gasket failure (between the head and intake manifold. They like to rust out the stock gaskets there. That's how the rear intake studs get all messed up from.

would you mind letting me know what u all are looking at to see that the coolant leak was from the lower intake plenum area? i am very much new to working on cars in general so have very little knowledge on what im looking at!!

 

[tootsie]

I'd be suspect of a head gasket issue on the rear cylinder on the passenger side (I think that's 5?). But yes, it also looks like you had a leak in the lower plenum and an o-ring leak on the front end of the coolant bypass pipe.

You can see the neglected cooling system from the rust in there... Looks like the PO didn't like coolant changes. I do see you were using Red/Pink most recently, which will be good going forward.

-Charlie

is there anything i could do to help clean out the rust in those passages besides more reg coolant changes with the red stuff?

 

[phattyduck]

is there anything i could do to help clean out the rust in those passages besides more reg coolant changes with the red stuff?

I don't have any specific suggestions. But the issues you are seeing are all often precipitated from years of cooling system neglect. (not that there aren't other causes too!). With the seals/gaskets fixed, I would get it running and then do some research on flushes that will work well for iron block / aluminum head engines.

-Charliei

 

[mtbtim]

I guarantee your symptom of white smoke blowing out after a cold start and losing coolant is due to the crack between the #3 cylinder valves. It happened to my truck, infamousRNR's truck and tons of others. It's a well-documented issue with these heads. Once you turn off the engine and let it sit over night, the cooling system is still under pressure. If that crack between the valves has migrated to a coolant jacket, which I do believe it has on your engine, the coolant slowly leaks onto the top of the piston. When you first start it up in the morning, that coolant on top of the piston can foul out the spark plug and cause a misfire until the coolant burns off. The smoke you are seeing is the coolant burning off, and once that's done, the smoke disappears and the exhaust looks normal again.

Take your heads to a shop that can vacuum test and pressure test them. I guarantee your passenger head is going to fail the pressure test. When they submerge that head under pressure, bubbles are going to be screaming out of that crack.

Go to play time 24:50 in my video and you'll see what I'm talking about. This was my buddy Sean's (infamousRNR) passenger head being tested.

 

[mtbtim]

I'd be suspect of a head gasket issue on the rear cylinder on the passenger side (I think that's 5?). But yes, it also looks like you had a leak in the lower plenum and an o-ring leak on the front end of the coolant bypass pipe.

You can see the neglected cooling system from the rust in there... Looks like the PO didn't like coolant changes. I do see you were using Red/Pink most recently, which will be good going forward.

-Charlie

Charlie, I'm surprised you didn't know that the coolant bypass pipe is not sealed to the block with an o-ring. For that connection, you use FIPG, 1282B to be precise. 1282B is the formula Toyota uses for engine coolant applications.