: Coolant leak under throttle body area?



N0DIH
11-17-06, 01:26 PM
A friend of mine has a 96 Deville N* with a coolant leak that seems to be under the throttle body. Are these common leakers?

chevelle
11-17-06, 01:55 PM
Not common at all. Look at the small hose connections to the throttle body heater. That may be the problem. The throttle body heater is required for throttle body icing in colder weather so do not disconnect or bypass it.

N0DIH
11-17-06, 02:26 PM
I will take a look. There wasn't enough I could see a drip, but I could see some stains on the intake just under the TB.

I agree, no power gains to ditching the TB heat, air flow moves too fast to be heated enough by it.


Not common at all. Look at the small hose connections to the throttle body heater. That may be the problem. The throttle body heater is required for throttle body icing in colder weather so do not disconnect or bypass it.

Gearheaad43
11-17-06, 10:33 PM
Not too sure on the N* TB.. but it's either the coolant bypass hoses OR the gasket that holds the coolant bypass housing to the body of the N* TB..
The 3.1/3100 GM V6 TB's are like this.

N0DIH
11-17-06, 11:43 PM
Does coolant go through the gasket itself?

Gearheaad43
11-18-06, 05:57 AM
Well, if it's anything like the 3.1/3100 V6's, the gaskets only serves to contain the coolant in the bypass. The coolant bypass only serves to bring the heated coolant close to the bottom of the throttle body to speed warmup / prevent freezing / binding of the linkage in extreme cold climates. Not even needed here in the lower US. .. Coolant DOES NOT circulate THRU the TB... Just close to it.

Ranger
11-18-06, 04:02 PM
I would not swear to it, but I think I recall the Guru saying that coolant DOES circulate through the TB on the Northstar.

AlBundy
11-18-06, 06:04 PM
I changed mine out a few months ago I had to remove the coolant lines and they looked pretty functional to me.

C170B
11-19-06, 10:48 PM
There is a sneaky little leak that can occur in the area of cocncern .TB

Two small short GREEN SILICONE hoses very short run under TB and connect to metal pipes on back side of engine. These hoses last 10-15 years.

At any rate you will notice a smell, "hot coolant" and cannot see any leak at all. Mystery.

One event is that a pinhole and I do mean tiny PINHOLE will develop and allow coolant to spray up on botom of TB and fill a valley under the TB. You can observe on passenger side of engine and cannot locate source.
With engine hot , raise hood and locate the small green hoses and just observe while the thermostat either closes or opens, it make a difference .

It does not leak all the time. Clean the hoses and start observing . Perhaps some one has posted a simple repair method. It took me a year to make correct diagnosis. By the way the metal pipes on back of engine are steel and can rust through. Most shops don't want this type work.

These hoses are 15.00 but they are 500.00 deep behind the engine.

I really hope this does not apply to you.

chevelle
11-20-06, 12:04 AM
Well, if it's anything like the 3.1/3100 V6's, the gaskets only serves to contain the coolant in the bypass. The coolant bypass only serves to bring the heated coolant close to the bottom of the throttle body to speed warmup / prevent freezing / binding of the linkage in extreme cold climates. Not even needed here in the lower US. .. Coolant DOES NOT circulate THRU the TB... Just close to it.


The Northstar throttle body heater is nothing like the 3800 or 3100 systems at all. It does NOT circulate coolant thru the throttle body nor the intake manifold directly nor does the gasket seal coolant.

The throttle body heater is required any time and any where the temperature could go below freezing....not just in places of extreme cold. It is best not to disconnect it.

N0DIH
11-20-06, 12:08 AM
Actually icing can occur even has high as 60F if the humidity is high enough. It is needed year round....

ewill3rd
11-20-06, 06:00 AM
I am not sure about your description of where this leak is coming from but it could be coming from the "crossover seals".
The water pump housing goes accross the back of the engine, there are 4 seals that attach it to the cylinder heads and they do leak after time.
It's probably one or more of those seals leaking. It's not an easy job and I think we usually charge between 5 and 6 hours of labor for it depending on the year.
I don't think the parts are too expensive but it's a royal pain because of lots of things that are in there. There is a heater hose that goes in the lower part of the crossover, EGR plumbing, and the water pump stuff along with the throttle body make for lots of things that are hard to deal with on this particular repair. You should be able to call for an estimate. Tell them you need to reseal the crossover or water pump housing and see what they give you for a price.
We see them pretty regularly.

Ranger
11-20-06, 03:59 PM
The Northstar throttle body heater is nothing like the 3800 or 3100 systems at all. It does NOT circulate coolant thru the throttle body nor the intake manifold directly nor does the gasket seal coolant.

The throttle body heater is required any time and any where the temperature could go below freezing....not just in places of extreme cold. It is best not to disconnect it.
Well, I stand corrected. So much for my memory. I guess I was thinking of the 3800.

Gearheaad43
11-20-06, 04:11 PM
The Northstar throttle body heater is nothing like the 3800 or 3100 systems at all. It does NOT circulate coolant thru the throttle body nor the intake manifold directly nor does the gasket seal coolant.

The throttle body heater is required any time and any where the temperature could go below freezing....not just in places of extreme cold. It is best not to disconnect it.

On the 3.1 (older version of the 3100/3400 family) the coolant is routed to a locaton UNDER the TB. The coolant DOES NOT flow thru it. There is a small bowl shaped chamber in which the coolant is circulated at the bottom of the TB. It heats up the TB by transfering heat to the plate. Probably a much simplier system than what the N* has.

ThisoldCaddy
10-19-11, 01:33 PM
I know some of you guys were mentioning you have experience replacing the water crossover seals and I was hoping to get some advice on that?

The water crossover is leaking on my 99 Cad Eldorado (4.6L). Do I need to remove the transmission linkage to replace the crossover on this car? It seems like I might need to pop that out of the tranny because it looks as though it's directly in front of the crossover bolts on the lower right hand side. It looks as though I can loosen the bolts but I'm not sure if there will be enough clearance to pull them out? Also, is it generally advisable to just replace the 4 seals on the crossover or is it recommended to replace or upgrade the crossover for any reason?

Thanks in advance

Submariner409
10-19-11, 02:04 PM
Nice find on a 6 year old thread...............good homework. Welcome Aboard !!! :highfive:

Go to Discussions, Item Specific: Cadillac Tech Tips - there are 10 pages of threads on How-to. You'll find one or more on this nasty job. The new seals are "redesigned", so they should last well beyond the originals. You have to pretty much remove everything off the rear end of the engine itself. Long day. Replace the throttlebody-to-intake manifold silicone seal ring while you're at it. Clean the throttlebody and passages. DO NOT use ScotchBrite pads for cleaning anything on or near an engine - they're impregnated with aluminum oxide dust, which eats mechanical parts alive.

ThisoldCaddy
10-19-11, 02:17 PM
Thanks for the tips submariner. I'll check out the Cadillac Tech Tips area as well.

postman2000
10-19-11, 04:02 PM
You should go to Autozone and rent a coolant pressure tester..That will help you tremondously...Thats what I do for coolant leaks..

ThisoldCaddy
10-19-11, 11:34 PM
Hey Submariner, I found the techtips forums you mentioned. I first tried the quick search of that forum for "how-to water crossover". I ended up with three pages and only one post related to my query. It has some photographs ewill put up of the crossover, but doesn't really get into the how-to part of the job. I then tried to find the information by manually scrolling through each post but came up empty. Are you sure there's a how-to under tech tips for this job?

Submariner409
10-20-11, 12:37 PM
Hmmmmmm............Somewhere there's a writeup on the water crossover gasket replacement. Either Tech Tips, in here, or maybe Seville - but it's engine related so it's probably in here. Pictures of the water crossover itself, too. The thing is also referred to as a water pump housing; depends on what page of what manual you're looking at !

Basically you drain the cooling system and start removing everything on the transmission end of the engine.

Use the procedure in the GM/Helm service manual or in www.alldatadiy.com (http://www.alldatadiy.com).

Ranger
10-20-11, 02:37 PM
Maybe this one will be of some help.
http://www.cadillacforums.com/forums/cadillac-seville-cadillac-eldorado-forum/208930-i-started-coolant-crossover-reseal-today.html