Cracked Block?

[Poobah]

After about 40,000 miles of trouble free driving, my '94 Eldo with Northstar gave me a "Check Collant Level" warning on the DIC.

I added water and the warning went away. I took it to my mechanic this morning to find out what caused the loss of coolant. He put the car up on the hoist and found coolant on the block around the oil sensor that is located low on the front of the engine block toward the right side. After pressure testing the cooling system, he said that the radiator is leaking a tiny stream of coolant and he thinks the block might also be cracked.

He said he has never seen a cracked aluminum block before but he thinks that might be the problem. I'm wondering if any of our members have had experience with this. (The engine has never overheated since the head gaskets were replaced 40.000 miles ago.)

How likely is it to have a leaking radiator and a cracked block at the same time?

How common are cracked Northstar engine blocks?

He is going to look into it further tomorrow morning.

Any words of encouragement at this point would be greatly appreciated.

Thanks in advance.

[Bruce Nunnally]

Why does he think the block is cracked? Is there a visible crack, or what symptoms suggest a cracked block?

[JasonA]

I guess the best words of encouragement would be that we haven't seen a cracked block here either...ever I don't think. A few unsubstantiated claims have come across the desk here in the past, but with no real validation.

I ask the same question as Bruce...ask him why he thinks there "may" be a problem with the block. Your mechanic is right -- aluminum blocks typically don't crack and seep coolant like that.

[adallak]

Fix the radiator and watch. Hopefully that will be all you need to do. I remember a couple of structural problems with 4.9 and Northstar, but they were really exceptions to the rule.

[BodybyFisher]

Actually we have seen a cracked block, remember PAT? The problem is we don't know how it was cracked, could it have frozen? Did someone put cold water in a HOT block?, something you DON'T want to do with and aluminum block.

Where is the crack they found?

[Ranger]

I agree, I have never heard of a cracked block. I would put the chances at slim. I am with Adallak. Fix the radiator and keep an eye on it. My money says it will be fine.

[Cadillac Jim]

If the radiator is seeping, coolant in small amounts can be found just about anywhere to sternward of the radiator. I would fix the radiator and do another pressure test. If the second test is good, then you are good to go.

[epricedright]

I was thinking the same thing, that maybe the radiator leak has sprayed coolant on the block, making the block appear to be leaking.

[Poobah]

An update:

I talked again with my mechanic this morning. He said the block is definitely cracked. The radiator is also leaking at the same time. (I'd probably have a better chance of winning the lottery than having all this happen at once!)

Before he left last night, he wiped the block off and he left the cooling system pressurized overnight. This morning, there was coolant on the frame under the radiator and along the front face of the engine.

He showed me a crack, or series of cracks, that runs from just above the oil level switch low on the right front face of the block almost all the way across to the bell housing at the left side of the engine. In some places, it looks to me like a series of hairline cracks.

There is evidence of dried, caked-on coolant running down from the crack in at least one place, as if it had been seeping there for some time.

He had no idea what may have caused it. I asked if it could be caused by detonation and he said he didn't think so. I am concerned about the detonation theory because I have had an ongoing, intermittant detonation problem with the car that I have not been able to solve. I have replaced the knock sensor and knock sensor wires but the problem persists. It won't seem to detonate for a mechanic, but it does occasionally, and sometimes severely for me. When I hear the knock, I take my foot off the gas to minimize it. I'm affraid I may have just let this problem go too long and am now facing the consequences. Any ideas on this?

Whatever the cause, I need to deal with the problem. The car is still drivable (for how much longer, I don't know). My next step is to take it to an independent Cadillac specialist for a second opinion.

I would appreciate any comments on this latest development.

Thanks,

[thu]

Maybe jumping a head here a bit, but how much is the car worth? Wondering if fixing it would be worth it. Wonder if you might be better off buying another car...

[BodybyFisher]

The severe detonation concerns me. Typically detonation involves the EGR system but that's water under the bridge now.

I wish you luck with whatever you do. I might be able to get you an engine if you are interested or are unable to get one out there in Cali... Mike

That is a standard Eldo, right 275 HP? That engine is easier to get than the 300 HP version

[KevinW]

He showed me a crack, or series of cracks, that runs from just above the oil level switch low on the right front face of the block almost all the way across to the bell housing at the left side of the engine. In some places, it looks to me like a series of hairline cracks.

There is evidence of dried, caked-on coolant running down from the crack in at least one place, as if it had been seeping there for some time.

The 'stream of coolant' observed from the radiator is likely the main source of the low coolant condition. From your description it sounds as if keeping the cooling system pressurized all night (not in itself a natural condition given the ambient temperature) has resulted in a small amount of seepage; I would repair the radiator, add six cooling system pellets, and not worry about anything. The GM Cooling System Supplement is ideal for addressing block porosity or hairline crack issues, and may have masked this issue earlier on. The efficacy of the supplement decreases with mileage, as the fibres are chopped by the water pump impeller.

I would say that any observed, audible detonation is irrelevant.

Kevin

[MAC]

He showed me a crack, or series of cracks, that runs from just above the oil level switch low on the right front face of the block almost all the way across to the bell housing at the left side of the engine. In some places, it looks to me like a series of hairline cracks.

There is evidence of dried, caked-on coolant running down from the crack in at least one place, as if it had been seeping there for some time.

The 'stream of coolant' observed from the radiator is likely the main source of the low coolant condition. From your description it sounds as if keeping the cooling system pressurized all night (not in itself a natural condition given the ambient temperature) has resulted in a small amount of seepage; I would repair the radiator, add six cooling system pellets, and not worry about anything. The GM Cooling System Supplement is ideal for addressing block porosity or hairline crack issues, and may have masked this issue earlier on. The efficacy of the supplement decreases with mileage, as the fibres are chopped by the water pump impeller.

I would say that any observed, audible detonation is irrelevant.

Kevin

I agree. I wouldn't write the car off yet.

[zonie77]

I agree with Kevin, add fresh tabs and replace the radiator. Then keep an eye on it.

[calif phil]

I was thinking the same thing, that maybe the radiator leak has sprayed coolant on the block, making the block appear to be leaking.

Is the crack on top of a coolant passage? I would bet that you might have a external leak or seep somewhere and it might look like a crack. A good mechanic will make certain before telling you something like that. Like the others said, fix the radiator and add some GM tablets.

[Bruce Nunnally]

JB Weld also claims to be able to seal block cracks:

http://jbweld.net/products/uses.php

[KHE]

I agree with KevinW - repair the radiator and add the GM pellets. If there are hareline "cracks", the pellets will seal them.

[Poobah]

Thank you all for the excellect responses to this thread. This is the true beauty of a forum like this - when you are faced with a major problem, there are others in our E-community who can give advise and council. I am appreciative of all the good suggestions you've given.

In response to thu's comment: I am looking at all my options at this point. It may be worth fixing or I may buy a newer car. I'm just not sure at this point.

One thing that has crossed my mind more than once lately is how much longer is 91 octane premium gas going to be available. This may sound funny but I'm not aware of any new cars that require premium fuel and my guess is that it won't be too much longer until some oil companies begin discontinuing premium. I went through this about 20 years ago when leaded premium was phased out. I was one of the last guys in town that used it.

I would hate to spent the 5 to 7 thousand dollars it would take to replace my engine only to turn around and have a hard time finding the right gas for it.

I am thinking of the incredible odds against having the block crack and the radiator spring a leak at the same time. I am leaning toward the theory that the block has been seeping small bits of coolant for a long time and the radiator recently sprung a small leak which set off the low coolant warning.

I think I will heed KevinW's, MAC's, zonie 77's, calif phil's, and KHE's suggestion and replace the radiator (possibly with a used one and do the work myself to keep the cost to a minimum), put in new coolant, add about 6 GM cooling system pellets and let 'er rip. My guess is that will keep it on the road for a while. If not, I'll look into Bruce's tip on the J B Weld. At least, I'm not out much and maybe I can enjoy my Eldo a while longer and put off my next car purchase until a better time.

I'll keep you all posted.

Thanks, again

[KHE]

I would not worry about premium gas being phased out. I think the Corvette and XLR cars still require it. Even if it did happen, which I doubt, your car can run on regular fuel.

[JasonA]

There are actually a lot of cars that require premium fuel. Many more than there used to be. The actual octane available varies by station. We have 91, 92, and 93 octanes available here in North Carolina.

I wouldn't worry about premium gas going away. The demand for it, by requirement, is actually more now than ever I'd say. Now, as far as people actually USING the recommended fuel or going for regular because of high prices, now that I don't know.

[Cadillac Jim]

In the 1970's I drove a 1969 Cheverolet 427 400 hp. For about a two-year stretch, high-test was impossible to get. When I drove to work and parked, the car would diesel for about 5 minutes when I parked it. I used to get a kick out of the circle of people around it that would inevitably form in the parking lot. It was a 9-passenger station wagon.

If it had been a more sensitive engine like a Northstar, I would have added octane booster from an auto parts store. I tried that once or twice and it worked OK. I didn't bother with that iron 427, I just backed off the throttle when I heard it ping. With a Northstar, I would add a bottle at every fillup.

On one long trip in 1989, I couldn't find high-test on the highway even though it was available in the cities by then. I found that, after about 1,000 miles, it would run just fine on regular gas, even WOT, without pinging. So, part of the solution is keeping clean combustion chambers.

OTOH, as KHE and JasonA say, it's all moot as far as planning and new cars go. In the early 1970's it was discontinued because it takes more crude to make a gallon of premium than a gallon of regular. That could happen again, I suppose, however remote the probability. I have an ETC which is preimum-only, and if necessary I will find a way to deal with it, with octane booster, combustion chamber cleaning, or both.

[zonie77]

I'd suggest a new radiator over a used one. New ones are not very expensive (compared to 20 yrs ago).

Your car should run OK on regular. Give it a try now and see how it runs.

If the cracks are small the JB weld should seal them. Clean them by sanding or actually grinding a small groove with a dremal type tool. You are only going .020" in so it will not weaken the block but it will give the JB a much stronger bond.

[GreenMachine]

the northstar will slow the timing is it detects that your starting to ping, you'll notice reduced performance and fuel economy by going to regular over premium.

One other thing to consider is your altitude about sea level. I believe the farther into the atomsphere you go, the less octane you need.

There are several cars the require, or suggest premium fuel. I belive the only cadillac that currently don't ask for premium over regular is the DTS. When I snooping around looking at manuals the STS asks for premium, the CTS asks for it, the XLR does, and the V-Series certainly do.

[Poobah]

I'll stop being concerned about the availability of premium gas. I wasn't aware that there are so many new cars that require it.

One more point: While making the arrangements for the radiator repair this morning, the mechanic winced when I said we should put in 6 cooling system pellets. He is concerned that the heavy dosage will clog the radiator. I know this issue has been discussed on this forum many times over the years - the pellets won't plug up the radiator because they don't solidify until they are exposed to air. Can anybody confirm this? I just like to be absolutely sure of what I'm doing when I tell a mechanic to do something that goes against his advice. (If something goes wrong, I know he'll just say, "I told you so.")

Thanks.

[JimD]

I'll stop being concerned about the availability of premium gas. I wasn't aware that there are so many new cars that require it.

One more point: While making the arrangements for the radiator repair this morning, the mechanic winced when I said we should put in 6 cooling system pellets. He is concerned that the heavy dosage will clog the radiator. I know this issue has been discussed on this forum many times over the years - the pellets won't plug up the radiator because they don't solidify until they are exposed to air. Can anybody confirm this? I just like to be absolutely sure of what I'm doing when I tell a mechanic to do something that goes against his advice. (If something goes wrong, I know he'll just say, "I told you so.")

Thanks.

For what it is worth, I will tell you the GM coolant supplement (or the Bars Leak Golden Seal powder) will not plug up anything except nuisance leaks.

Six tablets is not a heavy dose. You can double or quadruple that dosage without fear of causing a stoppage except at a potential leak source. Worse case is you will see some of the brown crud dropping out of solution in the coolant reservoir. And that is a good sign because it tells you that you have at least enough supplement in the system.

If your mechanic refuses to use the GM recommended procedure, do it yourself or find another mechanic.