konah

My wifes 4runner (5vz)has a noticeable coolant smell after driving. There is no noticeable loss of coolant or leaks that I can see. I seem to remember seeing a thread that mentions a leak somewhere towards the back of the engine. Could have been from a 3vz post.
The truck is an auto with 180,000 miles, all repairs and servicing is up to date. No overheating or abnormality.
Can anyone point me in the right direction?
Thanks.

rworegon

There is a coolant bypass tube that runs under the lower manifold and it may leak out the back of the engine. Use a telescoping mirror and a good light and take a look at the head to block interface.

5vz-fe leaking coolant at back of engine

Other areas: water pump, radiator, radiator cap, and overflow tank.

konah

Thanks rworegon. What you mentioned about the bypass tube under the lower manifold sounds right. I'll check that.
I read through the link you gave me. Great explanation and pictures. "IF" it is only the bypass hose leaking, what problems will it eventually cause? I will fix it, just not for a couple weeks yet.

vital22re

iTrader: (2)

more than likely the waterpump is starting to leak. There is a weep hole on the bottom of it. That is where it would weep from.

konah

Water pump was replaced 20,000 miles ago. Not saying that isn't the problem, just not very likely in my opinion.

rworegon

It will not really cause any problems other than leaking and filling that valley. Just keep a close eye on the coolant level.

If you determine you will go in there, plan on replacing the knock sensor wire. Heat kills 'em and it will be very brittle.

Check all the heater hoses and the heater valve. Also, there are two coolant lines attached to the bottom of the throttle body.

When I was smelling coolant, I had two small external HG leaks. The leaks were above the starter and on the back fenderwell corner of the driver side. Oh, and the valley had coolant in it also.

konah

I will check everything though, before tearing it down.

dropzone

iTrader: (6)

Had a similar smell in my old 97 taco..
Traced it to the heater core...

rworegon

Definately.....do the diagnostics....don't assume it's something major when it most likely something much easier.

Check the passenger floorboard for wetness which could be from the heater core.

dropzone beat me to the heater core while I was typing.

konah

I can only smell from the outside, or when windows are down. Just another thing to check.

konah

Could it be that I have too much anti-freeze in the radiator?

rworegon

Too much antifreeze as in the wrong ratio or too much volume? Excess volume just gets pushed to the overflow tank until needed. Maybe the overflow tank or tube is cracked?

konah

Too much anti-freeze as in ratio.

rworegon

Can't really see how to high of a ratio would cause you to smell it. It has to be escaping to the atmosphere someplace.

konah

Looks like I'll have to go with the original advice. Thanks all.

rworegon

Take a mechanics mirror and a good light and give the entire engine a good look along with removing the timing cover to look at the WP. It may be only a tiny spot of coolant crust that gives away the leak.

habanero

Does the 4Runner have rear heat? If so, check those lines for corrosion.
Also...
My 96 developed a crack in the radiator tank that was impossible to see unless hot. Took several days and eventual steam while sitting in traffic to figure that one out.
Good luck with an easy fix!