mdcflacal

Thanks for Looking.
I just bought a 1990 4runner with 117,000 miles.
The person I bought it from had the head gasket replaced about 1000 miles ago.
My question is minus the possibility of a head gasket leak, what else could be leaking on the back side of the egine bay? If it's a longer drive I haven't experienced any leaking(at least I haven't seen any steam rising up). I have seen it steam after about 5 minutes after start-up while waiting at a light or in traffic on a couple of occassions. In these cases before I could stop and check(5 to 10 minutes of driving) the leak would stop.
I haven't had any temperature problems and I haven't had any obvious signs that water is getting in the oil.

Do the head bolts need any re-tourqing after re-installing the head?
Anybody familiar with anything else that could leak back there in this manner?
Any suggestions would be greatly appreciated. I'm not completely new to working on cars, but I'm definitely still learning.
Thanks

JamesD

Search my user name.

James

mdcflacal

SRV1, I searched your user name but I'm not sure what you wanted me to see. should I search something more specific? Thanks

weakyota91

it sounds to me like it could possibly be 1 of the two heater core hoses going in to the firewall about middle of engine compartment. I had the exact same problem couldnt figure where my coolant was going for the longest time. spent 120 dollars at toyota for them 2 tell me i had a cracked heater core hose. The only reason I couldnt find it my self was it onlt leaked at higer rpm (while driving ) The reason it wouldnt drip on the ground at idle was it would drip on the exhaust and evaporate. hope u figure it out. leaks suck

Radyota

There's also a small upside down "U" shaped hose at the rear of the engine. It's down in the center (between the heads) and goes from a water distribution block with a few sensors in it down to a metal pipe that comes from UNDER the lower intake manifold (the block valley). It's hard to get to/see, but it's there. I hope it's a heater hose instead, because that little hose is awfully hard to get to. Good luck!

JamesD

https://www.yotatech.com/forums/f116/3-0-coolant-bypass-hose-rear-intake-68448/

James

mdcflacal

Thanks everyone.....any thoughts on pressurizing the coolant system to help locate the leak. Is this an effective method?

Silver_Truck

I've got the same problem...the thing is the leak is soooo infitisimally (sp?) small that I just said f it and I add an ounce of coolant every month. It's just way too much work for what its worth right now, if/when it gets worse I'll tear into it.

Platypus1

I had to pull the plenum 2 weeks ago in order to change the hoses back there. ITs the only way to get those stubborn yota clamps off, and have the leverage to pull those hoses off. FYI Toyota wanted $120 for 2 heater hoses back there, one of which was that tiny "U" shaped one. Instead I chopped off the ends on all the existing hoses, bought teflon tape, hi -temp sealant, and over sized screw clamps and re-installed them. So far so good.

I must say one thing, get ready for a roller coaster ride. As you begin replacing hoses, new leaks will occur in old ones until they are all fixed. I can't believe how much radiator pressure these trucks run at!

JamesD

I did mine without removing the plenum. You got to be creative! When I saw my u shape hose leaking I was damned if I was going to pull the upper intake off. It was harder this way but it was faster.

James

sandcrawler

i had the same problem a couple years ago and it was the hoses behind the manifold in the center of the engine compartment. replaced the hoses. fixed. good luck.

snap-on

I had the same problem. I couldnt get the hoses at a non stearlership so i bought a hose that had the 90 deg bend in it. I cut the old hose off mid lenght (good hose) Cut down the 3$ hose to use just the bend, then used a piece of 1/2" electrical conduit as a splice in the "straight" section of the hose with 2 clamps.

Its booty fab big time but has worked great for 3 years and has kept me from having to fight those damn hoses in the back again.

(at the time i was broke down in my office parking lot and a coworker drove me to and advance to get the hose at lunch)

mdcflacal

The hoses definitely sound like a great place to start....I'll let everyone know how it goes. I really hope that it works. Thanks again

abalagtas

I had the same problem as Radyota. I thought it was the HG and so did my mech because it was running so bad and the compression/leak test pointed to it. It was running bad because I had a cracked head and burned valves, but the leak was actually the U shaped hose. I think its the bypass that goes to some sensors. I found out later after they did the valve job because when I got home it was leaking from the same spot. My mech ended up cutting off the old one and putting on a new one w/o taking off the plenium. Took him like 5 minutes.

radrav4

mine was doing the same thing, it really is a PITA to get to, I remember it was my first time that I ever was layed out(chest on intake) with my arm behind the engine, wifey came out and just about died laughing...

mdcflacal

Hey everyone, I got the leak fixed. That hose is seriously jammed back there. Never understand why someone has the head off and doesn't bother to change some hoses. Thanks agian everyone

national

That U shaped hose was a breeze for me to get to but thats not my problem..still leaking but under that aluminum block peice..under the cross over pipe..I think from what Ive read that the lil metal line is probably my fault running under the intake..just wish I had some pics to show me more of what it looks like before I tear down to that far..

reggie 00

Mine does the same thing. I had the intake off and soldered it. I dont think it leaks as much, if at all like you said when you notice it by the time you get there to look its hard to tell.
The PO had it bypassed so thats an option if it gets to bad. Mine coorodied thru so not much chance of any real repair, short of getting a new one.
If mine starts up again its getting bypassed, not worth the trouble, doesnt seem to serve any usefull purpose anyway.

national

Would be great to by-pass it if possible..what would I do & where to by-pass it & would it do any harm to by-pass it..whats the purpose of the pipe & where does both small & big line go to from the rear of intake..where do they end up at..
Thanks,Brian

reggie 00

I'll go out and take a pic or two to show how mine was.