Coolant residue on intake manifold

[mike_m]

Have a 2000 4runner with 3.4 v6. Today I noticed that there's coolant residue on the intake manifold, front of motor passenger side near the temp coolant sensor. I was wondering if the intake gasket is going bad or other. Appreciate any suggestions. Attached a picture, apologize if it is too big etc. First time posting with pics.

Thanks

Mike M

 

[gamefreakgc]

If it's the front and there's no leakage from the coolant hose that goes through the bottom of the throttle body, then yes, that's most likely the issues. Could also see if the coolant temperature sensor somehow came loose, it's the sensor in the middle between the injectors.

 

[mike_m]

Thanks for the quick reply. yes at front and no not the tb coolant lines. I was hoping it might be the temp coolant sensor, but looking closely at it, that doesn't appear to be the culprit. To me it almost looks like the intake manifold bolt shown in the picture. Do you know if it's possible to be leaking from that bolt? According to my shop manual, it doesn't mention adding thread sealant to the bolt or if the washers are crush washers.

Thanks

Mm

 

[sleepydad]

Thanks for the quick reply. yes at front and no not the tb coolant lines. I was hoping it might be the temp coolant sensor, but looking closely at it, that doesn't appear to be the culprit. To me it almost looks like the intake manifold bolt shown in the picture. Do you know if it's possible to be leaking from that bolt? According to my shop manual, it doesn't mention adding thread sealant to the bolt or if the washers are crush washers.

Thanks

Mm

That is right where the ECT sensor is located but if that is not leaking?

The lower intake manifold might be cracked?

What about the main water outlet that goes to the radiator, there is a gasket Where it connects to the lower intake manifold.

If Its coming up From below it’s the water bypass, and that would suck. Your going to have to pull the lower intake to fix it. Might as well do knock sensor wire harness while your down that far.

 

[mike_m]

Pretty sure it's not the ECT sensor as it looks to me most of the coolant is around that intake bolt. I suppose it could be the main water intake gasket. I'll remove the timing cover and do some more investigating.. The truck has 246k and I've never replaced any of those gaskets. If I have to remove the manifold besides possibly replacing the knock sensors and wire harness, would it be a good idea to replace the gaskets on water bypass even if they are not leaking? Leak is pretty small. I lose about a 1 cup of fluid every 3k or so. Slow leak. thanks for the feedback. Also realize that it's one of those jobs where once I get into it, I might want to replace the original vacuum hoses, heater hoses, valve cover gaskets etc. and I'll get pricy pretty quick.

 

[gamefreakgc]

The bolt location is just coincidence. You could try replacing the front water pipe outlet gasket, all you have to do is take off the timing belt cover a bit and should be able to get to the 10 mm nuts.

But yeah, if it's the intake manifold that's not a small job.

 

[medusa3000]

Hi all I'm new to the forums and to working on 4runners/cars in general, so I'd like to ask this question for my own information: doesn't the intake manifold gasket prevent air from leaking out of the engine block vs coolant? I figured that the head gasket handled the fuel/coolant. Do I have the wrong idea?

Asking cause around a year ago I had an issue with my head gasket leaking coolant into one of the cylinders, which was a major pain because until I had the chance/money to take in to a shop, I had to periodically take the spark plug out of that chamber and stick a rag in to soak up the coolant, to prevent that cylinder from misfiring.

 

[sleepydad]

Hi all I'm new to the forums and to working on 4runners/cars in general, so I'd like to ask this question for my own information: doesn't the intake manifold gasket prevent air from leaking out of the engine block vs coolant? I figured that the head gasket handled the fuel/coolant. Do I have the wrong idea?

Asking cause around a year ago I had an issue with my head gasket leaking coolant into one of the cylinders, which was a major pain because until I had the chance/money to take in to a shop, I had to periodically take the spark plug out of that chamber and stick a rag in to soak up the coolant, to prevent that cylinder from misfiring.

the 5VZ engine has what toyota calls

Air Intake Chamber Assembly -> Intake Air Connector Assembly -> Intake Manifold Assembly

what we are talking about here is the Intake Manifold Assembly ( lower intake manifold )

it has coolant passages in it for sensors and cooling, it also connects the cylinder block to the radiator via the outlet on the Intake Manifold Assembly.

see diagram here

What your talking about is Cylinder Head gasket shown here in this image. totally different gasket but yes they are both connected to the cylinder block, but not the same coolant passages.

 

[St Runner]

There is also a couple of smaller coolant lines that run in and out of the Idle Air Control. Check to make sure those are not leaking

 

[catrains]

I have seen intake manifold bolts leak when 20 yrs old it happens . I pulled the bolt out put permatex thread sealant and leak stopped.

small coolant leak leaves small stains .verify wash it down and then check that it is the bolt .

 

[alumarine]

If you clean it off as catrains said and then rent/borrow a cooling system pressure tester that might help figure out where it's coming from.

 

[willywebster]

Im curious to know if you discovered the origin of the leak? and how you resolved it.

i have the same issue, im doing my timing belt and i noticed a similar coolant leak on the intake manifold

 

[jkoni426]

Im curious to know if you discovered the origin of the leak? and how you resolved it.

i have the same issue, im doing my timing belt and i noticed a similar coolant leak on the intake manifold

Just fixed the same issue, your intake manifold gaskets are leaking. Replace the gaskets and the knock sensor harness while you're in there.

 

[gamefreakgc]

That coolant looks fresh, looks like either the leak just started or is getting worse. Intake manifold gasket is the primary cause. The rubber seals around the coolant passageways corrode over time and fail.

 

[willywebster]

thanks for the responses guys!! i pulled timing covers off and the water pump was leaking and i have a sizeable coolant deposit just below the cam seal (i attached a few pics) any chance that the water pump leaked coolant onto the timing belt kicking coolant up and dumping on the intake manifold? or am i reaching?(im not real stoked about doing the intake manifold gasket)

im going to begin removing the plenum,i was going to do the valve cover gaskets any way so ill get a better look at things . if i do end up having to change out the intake manifold gasket is there anything other than the knock sensor wiring harness a guy should replace? like fuel injectors ect

 

[Mantilgh]

It is possible that coolant is being slung and blown around but it does seem like a lot though.

I’d say do the water pump because it easier and see what happens from there.


Sent from my iPhone using Tapatalk

 

[Bad Luck]

[MENTION=290372]willywebster[/MENTION] You're really grasping for straws. There's an extremely small chance that the coolant is making it from the water pump to your intake manifold. When you replace the intake manifold gaskets I wouldn't touch the fuel injectors (let alone replace them).

I see you're planning on doing valve cover gaskets which is a good idea while you're there. It would be a good time to do spark plugs/wires if you haven't done them in a while. I highly recommend getting a "spill free funnel" and using toyota red coolant. Now would be a good time to replace the radiator if it's the original or been in there more than 8 years for an oem or 5 years for an aftermarket. I'd also flush the cooling system with distilled water ($1/gallon).

 

[Captsolo]

https://www.amazon.com/gp/product/B01LWMM1Y7/ref=ox_sc_act_title_3?smid=ATVPDKIKX0DER&psc=1

https://www.amazon.com/gp/product/B00829I3TQ/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1

 

[willywebster]

[MENTION=290372]willywebster[/MENTION] You're really grasping for straws. There's an extremely small chance that the coolant is making it from the water pump to your intake manifold. When you replace the intake manifold gaskets I wouldn't touch the fuel injectors (let alone replace them).

I see you're planning on doing valve cover gaskets which is a good idea while you're there. It would be a good time to do spark plugs/wires if you haven't done them in a while. I highly recommend getting a "spill free funnel" and using toyota red coolant. Now would be a good time to replace the radiator if it's the original or been in there more than 8 years for an oem or 5 years for an aftermarket. I'd also flush the cooling system with distilled water ($1/gallon).

i figured i was reaching with the coolant fling theory.. i should have mentioned that the reason im in the engine this deep is im doing timing belt, water pump, cam/crank seal, belts, thermostat, radiator, pcv valve, valve cover gaskets, plugs, wires.. so im going to add intake manifold gasket and knock sensor wire harness to the list. thanks for input guys if anyone has any other good proactive things a guy should be adressing while things are torn appart id appreciate it

 

[gamefreakgc]

thanks for the responses guys!! i pulled timing covers off and the water pump was leaking and i have a sizeable coolant deposit just below the cam seal (i attached a few pics) any chance that the water pump leaked coolant onto the timing belt kicking coolant up and dumping on the intake manifold? or am i reaching?(im not real stoked about doing the intake manifold gasket)

im going to begin removing the plenum,i was going to do the valve cover gaskets any way so ill get a better look at things . if i do end up having to change out the intake manifold gasket is there anything other than the knock sensor wiring harness a guy should replace? like fuel injectors ect

Good catch on the water pump, they start leaking before they fail outright. Do you have a lot of miles on that rig though? It looks like it has seen better days with all those leaks.

No, it's not possible for a water pump leak to splash up top. Your belt would be slipping and squealing like mad if it was wet with coolant anyway. Water pump leak is unrelated to your intake valley leak.

All seals & gaskets are one-time use. Replace each gasket you have to separate (upper plenum, lower plenum, etc) and yes, make sure you replace all o-rings on the injectors. The o-rings are cheap and you don't want to be doing it all a second time because instead of coolant, fuel is filling up the intake valley!