Cooling System Leak

[JasonTL]

88' GMC Suburban 350 5.7L

Does anyone know how much coolant these hold?

I have a kinda interesting leak...When the car sits for a few days it will slowly leak about half a gallon of coolant(I only use water currently). The leak is on the driver's side of the engine and drips onto the oil cooler hoses and then onto the cross-bar between the front wheels. I don't know exactly where it is dripping from onto the oil cooler line. I need to go under there again and maybe use a mirror to see. Can't see much normally.

The Coolant does not leak while I'm driving. However it will start to drip about five minutes after I stop somewhere.

I've had a few suggestions that the problem may be bad/going freeze plugs. I'm not sure where these are though. It is hard for me to see anything on the bottom of the engine when I'm under there.
Are there any specific lines or connections on the driver's side of the engine I could check to see if they're the ones leaking?

Also(once I get this leak fixed) since I'm in GA, what mix of Anti-freeze/water should I do? 50/50?

Thanks

 

[Rhymingmechanic]

Freeze plugs are on the side of the engine block, below the heads. They are dished and circular, 2 or 3 per side, 2 on the front, and 2 in back, behind the trans.

I had to replace a bunch of leaking freeze plugs on an '87 Caprice, but I can't remember what path the coolant took. It would probably leak down the block to the oil pan rail, since the block angles in from top to bottom. I think there were obvious rust marks where mine were leaking.

I replaced at least one with a rubber expansion plug. It was difficult enough to punch the originals out with the engine in the car. There was no way to get a new one in straight.

 

[KB2008X]

From the standpoint of refilling a cooling system after draining, the old rule of thumb for a 50/50 mix is 1 gallon of coolant for a 4-cyl, 1-1/2 gallons for a 6-cyl and 2 gallons for an 8-cyl, and then add the same amount of water. Some vehicles will take a little more, some a little less, but those amounts are generally right on the money. When refilling my own vehicles I aim for a bit more than 50% coolant so if I should develop a small leak in the winter I can just add water until I get it figured out and fixed and still be OK as far as freezing. Be sure to drain and refill the side tank, too.

Do yourself a big favor and get a cooling system pressure tester, a good inspection mirror (on a stick) and a powerful light. It will take the guess work out of the equation and reveal the source of the leak much sooner.

Good Luck

 

[Donald]

Use no less than 50/50. If in super cold regions then 60 coolant)/40(water).

Best to use distilled water.

Water pumps weep before they really start squirting. They are designed to do that.

Another alternative is UV dye along with a UV light and funky yellow glasses.

That engine is one tough engine is you give it decent maint. Yours probably has 4 bolt mains since its basically on a truck. Thats the heavy duty version.

 

[surfstar]

Originally Posted By: KB2008X
From the standpoint of refilling a cooling system after draining, the old rule of thumb for a 50/50 mix is 1 gallon of coolant for a 4-cyl, 1-1/2 gallons for a 6-cyl and 2 gallons for an 8-cyl, and then add the same amount of water. Some vehicles will take a little more, some a little less, but those amounts are generally right on the money.


You haven't owned a tiny 4cyl. I'm at 50/50 with just over a half gallon of coolant in the system.

OP: Amsoil's website is great for finding specs on engines.

 

[JasonTL]

Originally Posted By: Donald
Best to use distilled water.

Just curious, why distilled?

Thanks all.

Unfortunately this engine was ran with mostly water for a few years in FL I believe. I've read that when run with 50/50 the plugs usually don't rust but when run with mostly water they do if they're the factory steel ones.

I went under the car today and traced the leak. Looks like the Freeze plugs on the left and right sides of the engine directly under(or above?) the engine mounts(I think that's what the brackets are) have rust trails coming from them. The passenger side definitely does, it was harder to see the driver's side one but I could see a rust trail on some of it at least.

I don't think there is any way to get those plugs out without removing the engine. I could try to get some pics tomorrow if it'd help.

I know it's only a temporary fix, but do y'all know if there is any sort of stop-leak I could use in the coolant to fix it and if so what are the side effects?

If it turns out I have to have the engine removed I'll have all the plugs replaced with brass ones(they don't rust, I believe) and will probably have some other work done on it. Unfortunately that'll likely be a hefty bill I hadn't planned on.

 

[tnt31]

GM Coolant Seal Tabs (Get from dealer or gmpartsdirect.com or I am sure other online places)

Bars Leak Tabs (most auto parts stores or Wal-Mart)

 

[KenO]

Ya, if it's been ran with pure water for a few years, chances are it's developed some rust inside. Before addressing the leak - personally, I'd do a strong flush to get any of the residual rust OUT of the system. Maybe a couple flushes. This might introduce a couple new leaks that were just waiting to spring up as soon as it cleaned itself a bit.


Once you do a strong flush and clean it out, I'd say go ahead and re-fill with water for now. As soon as it's refilled, get, as another poster said, a cooling system pressure tester. The parts stores sometimes have these for rent, but be weary, I'd found most of them leak and don't actually hold pressure themselves. Have to remember, tons of people are using these and rarely taking care of them.

As for coolant, it depends?? 50/50 is the generic mixture, it works well. If you do a lot of towing or generating a lot of heat, I'd recommend using less coolant, more water, and a bottle of Water Wetter. Water is a better conductor of heat, and the Water Wetter with both help the water remove even more heat from the engine, as well as help lubricate water pump bearings & prevent corrosion.

 

[JasonTL]

Originally Posted By: tnt31
GM Coolant Seal Tabs (Get from dealer or gmpartsdirect.com or I am sure other online places)
Bars Leak Tabs (most auto parts stores or Wal-Mart)

I found some Bars Leak Liquid Copper and Bars Leak Liquid Aluminum. They appear to be coolant additives. The reviews tend to say about 90% success rate. I couldn't find anything called a 'Leak Tab'. If either of these two might work I'd be willing to try them. My leaky freeze plugs are in a hecka hard to reach spot and I'm not sure if I could apply anything directly to them without just blindly rubbing my fingers on the spot.

Originally Posted By: KenO
Ya, if it's been ran with pure water for a few years, chances are it's developed some rust inside. Before addressing the leak - personally, I'd do a strong flush to get any of the residual rust OUT of the system. Maybe a couple flushes. This might introduce a couple new leaks that were just waiting to spring up as soon as it cleaned itself a bit.

How do you do a coolant system flush? Do you need special equipment?

Another question, will using a stop-leak additive screw any of my other systems or anything in the future? I've read that AC systems get messed up really bad when a stop-leak is used rather than a real repair. Could this cause really bad issues like that or is this more of a "It can't hurt" kinda thing?

Thanks for the info so far guys.

 

[KB2008X]

I'd avoid cooling system stop leak if at all possible. Stop leak is bad news in an otherwise well maintained vehicle, but particularly in your case. Running water only in the cooling system is likely to have partially clogged several spots in the cooling system where the passage ways become small and restrictive. Stop leak may clog one or more of them completely, because that is what it is designed to do.

However, sometimes a person has to use a stop leak and should you choose to take that risk the GM tabs that someone else mentioned are a good choice. Just be sure to use them properly and don't get your hopes up because the odds of any stop leak making it all the way to the freeze plugs aren't good

Replacing freeze plugs in the sides of an engine block can be a rather frustrating experience for a novice, but it is doable. Sometimes removing the exhaust manifolds will help, or removing a motor mount and then raising that side of the engine. Having the truck on a rack will make things easier.

Keep in mind that once you repair the obvious leaks that the next weakest link in that cooling system will start to leak. That may be the freeze plugs at the rear of the engine, some of which are accessible only by removing the transmission.

 

[SteveSRT8]

While I would agree about using stop leak in a vehicle not designed for it as a last resort we have used the GM pellets for ages in fleet trucks per the service manual and have never had an issue.

I think the key is following the mfgr recommendations regarding the cooling system. If you start experimenting expect issues.

 

[Rhymingmechanic]

On my Caprice, this job involved lying underneath and pounding with various chisels and even a curved bar my friend had made for some other job. I took off at least one motor mount--it seems like there was a plug right behind it.

It took me a day or two, but I eventually got the leakers out. I don't remember whether I replaced all or just some with rubber expansion plugs. This was a $1000 car. The previous owner said he'd had some freeze plugs replaced, so maybe they did the easier ones.

 

[tnt31]

Originally Posted By: JasonTL
Originally Posted By: tnt31
GM Coolant Seal Tabs (Get from dealer or gmpartsdirect.com or I am sure other online places)
Bars Leak Tabs (most auto parts stores or Wal-Mart)

I found some Bars Leak Liquid Copper and Bars Leak Liquid Aluminum. They appear to be coolant additives. The reviews tend to say about 90% success rate. I couldn't find anything called a 'Leak Tab'. If either of these two might work I'd be willing to try them. My leaky freeze plugs are in a hecka hard to reach spot and I'm not sure if I could apply anything directly to them without just blindly rubbing my fingers on the spot.

Originally Posted By: KenO
Ya, if it's been ran with pure water for a few years, chances are it's developed some rust inside. Before addressing the leak - personally, I'd do a strong flush to get any of the residual rust OUT of the system. Maybe a couple flushes. This might introduce a couple new leaks that were just waiting to spring up as soon as it cleaned itself a bit.

How do you do a coolant system flush? Do you need special equipment?

Another question, will using a stop-leak additive screw any of my other systems or anything in the future? I've read that AC systems get messed up really bad when a stop-leak is used rather than a real repair. Could this cause really bad issues like that or is this more of a "It can't hurt" kinda thing?

Thanks for the info so far guys.


Bars Leak Tabs
Bars Leak Tabs at O'Reillys

Or just go to any GM dealer and get some coolant seal tabs.

 

[JasonTL]

Thanks guys.

Both of my plugs on under the engine mounts. I do not have a lift nor an engine hoist(may have a friend that I could borrow the hoist from). Would it still be possible to remove one mount at a time to reach these?

If I can replace them without removing the engine, I'll probably use the rubber expansion ones. If I have to remove the engine I will replace all of the freeze plugs with new copper ones.

Those Bars Leak tabs are made from Ginger root and something else I think I read somewhere, right? They might not screw my system as bad as actual stop leak, perhaps?

I know the only real cure is to replace the freeze plugs with good metal ones, it's just I don't really have the funds for that ATM and am hoping I can get something to last for 6 mo-a year while I budget for the real repair(and also schedule some other repairs at the same time if the engine has to be removed).

I will definitely be running only 50/50 Antifreeze/Distilled water after I get this fully fixed. Don't like what that solo tap water has done over the years.

 

[Rhymingmechanic]

You can undo both mounts from the frame, then raise the engine with a floor or bottle jack--with a block of wood between the jack and oil pan. A hoist might be safer and easier on the pan, though. Then you would remove the offending motor mounts from the engine to access the plugs. Taking off the frame-side mount might give you more room to work.

However you raise the engine, be conscious of what's connected to it and what makes contact first--in a car, that's usually the distributor and the firewall/transmission tunnel area. The Suburban might have more room. Be careful not to stretch or pinch any wires or hoses.

I remember snugging the nut on one of the rubber plugs at oil change time, but never had any more problems. I didn't think to use a stop leak, but the GM tabs might be a good suggestion considering the engine's history.

 

[JasonTL]

I ordered some Bars Leak Tabs from Amazon, should get them Wednesday.

I drove it to a friends ~10mi away and then drove it back home about 3 hours later(I know, short trip), didn't check the fluids between drives. I did check the coolant before I left initially and filled the radiator to almost full and filled the reservoir to the line. When I checked it today the reservoir was mostly empty but the radiator was about where I had filled it to. I refilled the reservoir and added a bit more to the radiator today. I'll check it again on Wednesday.

Full repair is on the list and perhaps still necessary but I want to try the tabs. I'll do a few good flushes when I get the plugs actually replaced as there is definitely noticeable rust/dirt particles in the system.

 

[Rhymingmechanic]

I just read my last post, and realize it's not very clear. To raise the engine, you would first remove the large horizontal bolt that holds the two motor mount pieces together--there's one bracket on the engine and one on the frame.

I hope you can get by with stop leak until you can pull the engine--especially if there's more work to be done. When I did mine, I replaced what I could and kept my fingers crossed that the plugs behind the transmission wouldn't start leaking.

 

[JasonTL]

Originally Posted By: Rhymingmechanic
I just read my last post, and realize it's not very clear. To raise the engine, you would first remove the large horizontal bolt that holds the two motor mount pieces together--there's one bracket on the engine and one on the frame.

I hope you can get by with stop leak until you can pull the engine--especially if there's more work to be done. When I did mine, I replaced what I could and kept my fingers crossed that the plugs behind the transmission wouldn't start leaking.

I think I know what bolt and bracket you're talking about. It did look like a two-piece thing and I was hoping it would be able to come apart.

I know I have a small oil leak into the exhaust/combustion system somewhere(evidenced by white/greyish exhaust). Haven't really started diagnosing that can of worms much.
I also have a sound which I'm thinking is a noisy lifter. Again, haven't spent much time diagnosing it.

When the engine is pulled I'll try to do as many repairs and maintenance things as possible.

 

[crazyoildude]

+1 if the leak cant be easily fixed and its not coming from a hose

 

[Brad_C]

I know I'm late to the partyon this thread, but if you want a cheap / fast fix that is far more reliable than the goop you put in the system, and you don't or can't replace the plugs right now, drain the system, clean the plugs well with a wire brush and jb weld them. The jb weld can then be removed when you do replace the plugs, but in the mean time you have a very good chance of stopping the leak. Don't use the 5 minute stuff and don't use any other epoxy.

Make sure you re-fill with a good anti corrosive.