Leaking Coolant from Throttle Body Preheat Line

[88 EA82T]

I have an '88 GL10 with the MPFI turbo setup. I had the intake manifold gaskets replaced about 6 months ago along with the throttle body preheat coolant line. The preheat coolant line is now leaking at the end coming from the thermostat housing. There was enough slack in the line that I could take the hose clamp off, cut the hose and put it back in with a new hose clamp. That worked for about 2 weeks and now it is leaking again. When I pulled the line off to change the hose clamp, it seemed like the hose was loose going onto the barb and that the guy just tighten the crap out of the hose clamp when he put it back together.

 

So does anyone know what the correct size for that coolant line is supposed to be?

Is the only way to replace that line to remove the intake manifold?

Can I reuse the intake manifold gaskets?

Is it a tough job to remove the intake manifold?

Why does this always happen to me???

[88 EA82T]

Update; went out at break time to top off the coolant. It was down about 1/2" in the overflow jug and it was low in the radiator so I topped it off then started the engine to get any bubbles out. Seemed to be fine, shut it off started walking back inside, stopped talk to a buddy for a couple of minutes, looked back and there was a puddle of antifreeze under the car.... Not good. I really thought it was the throttle body preheat line but seemed to be dry on both ends. I can't see any leaks and all of the hoses I can see look to be dry? I can see antifreeze on top of the block and under the intake manifold on the passenger side but I really don't see where it is leaking from?

 

I really need some help here. Any ideas?????

[idosubaru]

i remove the throttle body preheat lines. remove them and just run one hose instead of two to bypass it all.

 

sounds like you now think that isn't your problem. you need to narrow down where it's coming from.

 

pretty sure there's a tiny little hose underneath the alternator somewhere - or top center just a little to the left since some alternators can be located differently.

 

if you really can't find it - then remove some of the stuff up front like alternator, power steering, a/c, and their brackets will allow you much better visibility under the intake manifold. if you're not wanting to do that....then apparently the leak isn't bad enough yet, just wait until next year!

 

the intake manifold gaskets have water passages through them that can leak as well.

[john in KY]

Also a line that runs to the turbo. My money on this one and it is a bear to replace.

[GeneralDisorder]

Love those pesky turbo coolant hoses .

 

Go to the dealer and order EVERY SINGLE coolant line on the car. Save you a lot of headache and blown head gaskets.

 

GD

[MilesFox]

You would be looking at 1/2" hose for the turbo coolant lines. You would have an easier time if you removed the '4wd turbo' plenum, and removed the belt from the alternator and swing it up and out of the way.

[88 EA82T]

So I did some more looking around for the leak and it is not any of turbo coolant lines, all those were replaced in the last 6 months. I topped off the coolant and ran it again for about 5 minutes and shut it off. Coolant started running off the back of the block on the passenger side and pooled up on the block between the thermostat housing and the throttle body. I was able to get a finger on the throttle body coolant line that is under the intake manifold and now I am sure that is where my leak is. The pictures shows the line that disappears under the intake. So I guess the next step is to pull the intake manifold...

 

So how hard is it to pull the intake manifold?

How much stuff do I have to pull off first?

Or will most flex enough I can get in there to replace the hose?

Can I reuse the intake manifold gaskets (they should be OEM)?

 

I think the source of my problem is when the guy replaced my intake manifold gaskets he replaced the throttle body coolant line but used 3/8" hose instead of 1/4" and tighten the crap out of the hose clamps. worked ok for a couple of months....

[MilesFox]

If you have the right screwdriver, you should be able to reach that hose by taking up the power steering pumpp, or just getting in there carefully. It can be done without removing the intake.

 

make sure the hose you use is not fuel hose or you will have the same problem down the road

[88 EA82T]

Well, I think I got it fixed. I ended up pulling the line off with some channel locks with the hose clamp still on it. There was no way I could get in there with a screwdriver to loosen the hose clamp on the intake manifold side. So the line was definitely not the right size, see the picture. The 1/4" line was pretty hard to get on so I cut it to length and put a screw driver in the line and used that along with my fingers to force the line on to the hose barb. Then I used a spring clamp to hold it on that end since there was no way to get a screw clamp in there and tighten it. Topped off the antifreeze and went for a test drive. No more leaking.

 

I win, finally and I didn't have to remove the intake manifold... Car made it 20 miles to work just fine so I will check the coolant level before I head home. Thanks for the help.

[MilesFox]

Glad to see you got it done without too much complication. +1 for the spring clamps.

 

If you have to do this hose again, or others like it, try a 5/16" hose

[88 EA82T]

Coolant level checks out good and there is no green stuff on top of the block. Hopefully that is the end of things for awhile....