LSCHMIDT

Coolant is coming out at the rear of my '94 LT1 engine. It appears to be leaking from the line that connects the cylinder heads together. Anyone else had this problem? Is it a difficult repair?

Mez

I just completed the removal and installation of my heads last night, so I had to remove and reinstall the coolant vent line on the back of the heads.

For those not familiar, starting with the LT1 reverse cooling system, the engineers added a steel coolant vent line to the back of both heads. The purpose is to vent air or steam that can accumulate in the heads back to the radiator. The line runs from the back of both heads, along the intake manifold passenger side, to a rubber hose into throttle body, then out of the throttle body to the radiator. The throttle body by-pass modification routes the coolant directly back to the radiator.

The lines are bolted to each head with a unique "banjo" type bolt. This type of bolt is drilled out in the center and has two holes drilled laterally to route coolant from the heads into the steel line.

To seal the bolts and lines to the head, two special washers are used per side. One washer under the bolt head and one at the cylinder head. These washers have a rubber center with a outer steel ring. I bought all 4 at the local Chevy dealer last week that cost....make sure you are seated....$7.18 + tax each!

In your case, I would first try retorquing the bolts. The torque specification is 30 ft lbs. You can get at them fairly easily with a box wrench. If that does not work, you may have to replaced the washers. If you replace the washers, one most likely will be stuck to the head. So you have to feel back there or use a mirror to check. Once you peal them off, it may be necessary to clean the area on the heads where the old washers left some rubber.

Make sure you clean the threads of the banjo bolts and then reinstall with pipe thread sealant.



[Modified by Mez, 12:43 PM 11/16/2001]

LSCHMIDT

Thanks for the information. The right head bolt is rounded off. I guess that the previous owner had problems with this before. I hope to get the bolt out and replace it and the washers.

GlockLT4

"For those not familiar, starting with the LT1 reverse cooling system, the engineers added a steel coolant vent line to the back of both heads. The purpose is to vent air or steam that can accumulate in the heads back to the radiator. The line runs from the back of both heads, along the intake manifold passenger side, to a rubber hose into throttle body, then out of the throttle body to the radiator. The throttle body by-pass modification routes the coolant directly back to the radiator."

I think you are referring to the LT4. My LT1 has no steel coolant lines going to the TV, and nor do any that I've seen. The hoses that that coolant comes from are the heater core (that or the pressure reservoir -- can't remember off the top of my head) and the other side connects to a T in the upper radiator hose. There is one small steel coolant line that comes off of a T around the pressure tank and goes back to the rear of the passenger side head.

The LT4, on the other hand, doesn't have the T in the upper radiator hose and has steel lines as you said.


[Modified by Glock'94, 7:15 PM 11/16/2001]


[Modified by Glock'94, 1:38 PM 11/17/2001]

your drinking buddy

Try this leak: no puddles under car at all, but the dang coolant is going somewhere! :smash:

GlockLT4

DOH! that's bad.... blown/blowing head gasket.... You should check for any steam at all in your exhaust. And also check your spark plugs for moisture.


[Modified by Glock'94, 7:33 PM 11/16/2001]

darkredlt1

Last weekend, I noticed a small puddle of liquid where the car had been parked and I wasn't sure if it was from mine or not. Anyway, I noticed a larger stain yesterday coming from the front and thought that the mechanic had left something loose after replacing the opti and water pump a couple of weeks ago. I drove the car to the Chevy store and we found that a water hose had a small hole and it had just gotten worse. The underside of the hood was wet. I got lucky. We checked all the other hoses and they were ok. The car is 8 years old (115,000 miles) and still has the original hoses. Is there a schedule for changing the hoses? This is one of those times that I would rather be safe than sorry.

RadPolo96

My coolant is leaking from my water pump and I now have to replace the pump is cuz the seal inside busted and is leaking fluid out and onto the belts. The belts are then spraying it all over engine. Fun Huh :rolleyes: So now I have to try and make it to the repair shop without car overheating and hope fluid doesnt get on optispark :cry

Shark ssn591

BAD BAD BAD... Do a pressure check NOW you must find the leak!!!!!:eek: :eek: :eek:

If you don't see it on the ground here are the likely choices...
1) you get a lucky break and it is slowly leaking out the water pump (seal) or a hose and steaming off the engine when it is hot, you can tell this cause when it is hot you smell the glycol (especially in the engine compartment) :) (please be this one)

or blown head gasket due to warped head:
2) look @ the OIL (look for the streaking on the dipstick and an increase in oil level : water don't lube like oil.....you get the picture :cuss
3) It's getting burned in the cylinder, look @ the exhaust, white smoke and the glycol smell...It'll probably kill the O2 sensor soon but if you get enough H2O in the cylinder (water being NON-COMPRESSIBLE), your gonna pound the heads right off the engine, may even break a piston and/or bend a connecting rod :cuss

4) You are the luckiest SOB on the planet, when driving, the coolant expands into the coolant recovery tank, but the tank leaks, when you park it, it vacuums air into the radiator.
:cheers:



[Modified by Shark ssn591, 9:22 AM 11/17/2001]

RadPolo96

Mine was option 1 :sad:

Thud

I had a mystery leak on my LT1 too. I noticed the overflow tank was bone dry. But no puddles, and no tell-tale coolant sprayed on the underside of the hood (which usually means the water pump is going).
Coincidentally, my passenger headlight was having trouble opening and closing too. But what I discovered was that the metal line going into the overflow tank was coming off the tank (didn't tighten the clamp enough last time) so coolant must've been spilling out on its way bank down there. And since the metal line was sticking up an inch higher than it was supposed to, the headlight was running into it on its way around.

Anyway I pushed the hose back down, tightened the clamp, added coolant, and it hasn't lost any more since then... and the headlight works too!

GlockLT4

Lets hope it's number 4!!! :eek: :eek:

your drinking buddy

Theres nothing in the oil, but oil. :D It's at the same volume it was when I changed it about 2 weeks ago. No steam in the engine bay or a weird smell. No steam or colored exhaust when she warms up. Although, when she is first started in the morning, the exhaust is white and will stay white until it warms up to about 140*.

Just checked the connections and they look fine, nice and tight. The recovery tank seems to always be at the cold mark, even after I had driven it.

On a side note, my mom's Land Rover is also leaking coolant. Going out now to check it out.

your drinking buddy

Does anyone think I may need a new radiator cap? I noticed right under it there is what looks to be dried coolant. It's greenish in color.

LSCHMIDT

I haven't been able to get the bolt out from the back of the head that holds the line to the head. Just to be sure, is the bolt right or left hand thread?

corvette1990

I have had many of those options for coolant loss in the last 3 years. First it was the waterpump. Then I had the intake gaskets replaced cause it was puddling on the passenger side front area. Next when it was drinking like half a gallon per 100 miles, I found it running out of cylinder number 7 spark plug hole (blown head gasket). the back of the 350 gets too hot apparently. New engine. Few months later (last week) I notice antifreeze green puddling by thermostat. I curse the mechanic who cant hear me. I pull the throttle body off to get to the thermostat housing and find that a small bolt has fallen from the bottom of the throttle body, and the throttle body is not only loosing antifreeze it is also allowing antifreeze to be sucked into the intake. :U . It is presently all better now. :D

Shark ssn591

hey corvette1990
That is a new one on me...:cool: . Wow the unique Corvette design shows a new leak and "disposal" (hide the leak) process. I like it... sounds hard to diagnose, but once you found it made sense eH?? ;)


[Modified by Shark ssn591, 7:32 AM 11/18/2001]

Shark ssn591

Greetings there vettes rule


An old trick from an old timer (ME)

{sorry I forgot to mention it but I am working nites & this ole brain ain't as sharp as it used to be}

With the engine off, remove the radiator cap.

Have a friend crank the engine, If coolant sprays out of the radiator (due to compression pressure) your problem is a head gasket (or a cracked block :U ). Absense of this "spray" doesn't totally rule out the gasket but It is a quick check to see if it is already a VERY BAD DAY :cry :cry :cry

Shark ssn591

You may succeed in getting to the shop w/o additional damage... But the voice of experiencee sez....TOW IT, warped heads makes this job COST ABOUT 2k, and from what I have read on this Forum, that OPTISPARK isn't a free lunch either.

your drinking buddy

Shark, no coolant splashed out. It seems to only leak at times, not others.