Cracked/leaking intake?

[wiplash]

I just picked up a '98 Seville STS with 176k on it for $1800. The dealership selling it said the intake was cracked or leaking into the combustion chamber (via the intake runner in the head). I talked with his mechanic who diagnosed it to see how he ruled out a head gasket and here's what he said;

He did a hydrocarbon test on the coolant and caem up with 40ppm, he said typical HG failures show 2500+ ppm.

He pressurized each cylinder with 120psi and each one held.

That's all I know from him, which is all hear-say. Here is what I know;

There are no bubbles coming up into the surge tank,

The car does not overheat (it will get a little warm, a little past half, then go back to wherre it should be), but it is only 40* here.

Car is steaming coolant out the tailpipes, not much but enough to know it's there,

It runs rough upon startup, for maybe 10 seconds then it's good.

There's a check engine light on, which I'll check on Monday to see what it is.

There's no heat in the car, it seems as though the coolant system isn't under a lot of pressure, definately not 16psi.

Thanks for your help guys.

[KHE]

There are NO coolant passaged in the intake manifold... I assume you smell burning coolant in the exhaust?

I would pressure test each cylinder - you'll know for sure if the head gaskets are bad.

[growe3]

The intake may or may not be cracked, which can cause rough or irregular running, but....that has nothing to do with coolant in the combustion chamber. The Northstar does not have coolant running through or under the intake manifold.

If you are getting coolant out of the tail pipe, it is obviously getting into the combustion chamber somehow, the only ways I can think of are (1) bad head gasket (the most common), (2) cracked head (very rare) or (3) cracked cylinder liner (very rare).

Steam out of the tail pipe is normal during warm-up. particularly on cold days. Smell the vapor coming out of the tail pipe, if it is coolant it will smell sweet, water vapor has virtually no smell.

If the car does not over heat, why do you think it has a coolant problem?

As to some roughness, have the spark plugs been replaced? It should be due for its third set, it is highly recommended to use the OEM AC Delco ones.

Do the spark plug wires need replacing? With the engine running in a dark area or at night, can you see arcing between the wires and/or the heater motor? All signs of bad wires.

-George

[Ranger]

Don't overlook the purge line and the FPR. Both are easy to check.

[wiplash]

The intake may or may not be cracked, which can cause rough or irregular running, but....that has nothing to do with coolant in the combustion chamber. The Northstar does not have coolant running through or under the intake manifold.

If you are getting coolant out of the tail pipe, it is obviously getting into the combustion chamber somehow, the only ways I can think of are (1) bad head gasket (the most common), (2) cracked head (very rare) or (3) cracked cylinder liner (very rare).

Steam out of the tail pipe is normal during warm-up. particularly on cold days. Smell the vapor coming out of the tail pipe, if it is coolant it will smell sweet, water vapor has virtually no smell.

If the car does not over heat, why do you think it has a coolant problem?

As to some roughness, have the spark plugs been replaced? It should be due for its third set, it is highly recommended to use the OEM AC Delco ones.

Do the spark plug wires need replacing? With the engine running in a dark area or at night, can you see arcing between the wires and/or the heater motor? All signs of bad wires.

-George

So there's no coolant running through the intake, or even the throttle-body to cool the EGR?

The reason's I believe there's a coolant problem are 1) Steam out of the tailpipes, I smelt it once when I was checking out the car, and it smelt faintly of coolant (I've blown many a headgasket in my supercharged Ford's). 2) Coolant system is not under full pressure, I'll hook a pressure gauge up to it tomorrow to see where it's at 3) Heater core is not getting a very strong flow of coolant, which I am assuming is due to the low system pressure

The check engine light could be from a misfire from the leakiing cylinder if that were the case, correct. Like I said, I just picked it up so I'll have more time to look into these things in the next few days.

On a side note, the car was bought at an ausction, where the previous owner had ONLY the Valet key! Can the dealership hook me up with the correct chipped keys and key-less entry? And is the Valet key the reason speed is limited to 90mph, the "Service Suspension System Soon" warning is on as well?????

[KHE]

The intake may or may not be cracked, which can cause rough or irregular running, but....that has nothing to do with coolant in the combustion chamber. The Northstar does not have coolant running through or under the intake manifold.

If you are getting coolant out of the tail pipe, it is obviously getting into the combustion chamber somehow, the only ways I can think of are (1) bad head gasket (the most common), (2) cracked head (very rare) or (3) cracked cylinder liner (very rare).

Steam out of the tail pipe is normal during warm-up. particularly on cold days. Smell the vapor coming out of the tail pipe, if it is coolant it will smell sweet, water vapor has virtually no smell.

If the car does not over heat, why do you think it has a coolant problem?

As to some roughness, have the spark plugs been replaced? It should be due for its third set, it is highly recommended to use the OEM AC Delco ones.

Do the spark plug wires need replacing? With the engine running in a dark area or at night, can you see arcing between the wires and/or the heater motor? All signs of bad wires.

-George

So there's no coolant running through the intake, or even the throttle-body to cool the EGR?

The reason's I believe there's a coolant problem are 1) Steam out of the tailpipes, I smelt it once when I was checking out the car, and it smelt faintly of coolant (I've blown many a headgasket in my supercharged Ford's). 2) Coolant system is not under full pressure, I'll hook a pressure gauge up to it tomorrow to see where it's at 3) Heater core is not getting a very strong flow of coolant, which I am assuming is due to the low system pressure

The check engine light could be from a misfire from the leakiing cylinder if that were the case, correct. Like I said, I just picked it up so I'll have more time to look into these things in the next few days.

On a side note, the car was bought at an ausction, where the previous owner had ONLY the Valet key! Can the dealership hook me up with the correct chipped keys and key-less entry? And is the Valet key the reason speed is limited to 90mph, the "Service Suspension System Soon" warning is on as well?????

Simultaneously press and hold the OFF and INFO UP (I think...) to display the codes. The dealer can make you a proper ignition key or two.

The lack of heat could be from low coolant or improper coolant concentration - have you verified the proper level of coolant (2-1/2" beow the neck of the surge tank)? You are only assuming the heater core is not getting the proper flow of coolant.

[Ranger]

The check engine light could be from a misfire from the leakiing cylinder if that were the case, correct?

Not necessarily. A mild misfire won't trip the SES light.

So there's no coolant running through the intake, or even the throttle-body to cool the EGR?

No.

The reason's I believe there's a coolant problem are 1) Steam out of the tailpipes, I smelt it once when I was checking out the car, and it smelt faintly of coolant (I've blown many a headgasket in my supercharged Ford's). 2) Coolant system is not under full pressure, I'll hook a pressure gauge up to it tomorrow to see where it's at 3) Heater core is not getting a very strong flow of coolant, which I am assuming is due to the low system pressure

This plus the fact that it came from an auction is troubling. If the head gasket is bad and pumping exhaust gas into the cooling system, that would explain the lack of heat (air rather than coolant in the core). I'd do a cylinder pressure test.

[wiplash]

Simultaneously press and hold the OFF and INFO UP (I think...) to display the codes. The dealer can make you a proper ignition key or two.

The lack of heat could be from low coolant or improper coolant concentration - have you verified the proper level of coolant (2-1/2" beow the neck of the surge tank)? You are only assuming the heater core is not getting the proper flow of coolant.

Coolant level in the surge tank WAS a little low, I filled it to the proper level and I get a LITTLE heat when rpm's are above 2500.

Coolant out of the tailpipes seems to be only on startup and 15-20 sec later, after it's fully warmed up there is no trace of coolant in the exhaust.

I am assuming the heater core isn't getting proper flow just by touching the inlet/outlet hoses, they're luke warm when the engine is up to temp.

The check engine light could be from a misfire from the leakiing cylinder if that were the case, correct?

Not necessarily. A mild misfire won't trip the SES light.

So there's no coolant running through the intake, or even the throttle-body to cool the EGR?

No.

The reason's I believe there's a coolant problem are 1) Steam out of the tailpipes, I smelt it once when I was checking out the car, and it smelt faintly of coolant (I've blown many a headgasket in my supercharged Ford's). 2) Coolant system is not under full pressure, I'll hook a pressure gauge up to it tomorrow to see where it's at 3) Heater core is not getting a very strong flow of coolant, which I am assuming is due to the low system pressure

This plus the fact that it came from an auction is troubling. If the head gasket is bad and pumping exhaust gas into the cooling system, that would explain the lack of heat (air rather than coolant in the core). I'd do a cylinder pressure test.

There seems to be no exhaust gas traces in the coolant (according to the mechanic, and there certainly aren't any bubbles in the surge tank when the car is running, cold, warm or otherwise.

And for the price I payed for the car I'll have no problem replacing the motor if the head gaskets are bad, the rest of the was too sweet to pass up.

[JasonA]

It does sound like the coolant may be low elsewhere in the system (air bubble perhaps). I like your attitude though -- if you got the car for a real steal, you could certainly afford to replace the engine and still be financially ahead on a fantastic car. Even if it is head gaskets, the typical repair calls for Timeserts and new gaskets. No need to truly replace the engine, or get into machining the deck or replacing bearings in the bottom end, etc. These engines have absolutely bullet-proof bottom ends.

[BodybyFisher]

Is a Cadillac dealer selling this car? They must know no coolant runs through the intake.

As someone else said, the purge line if clogged won't allow the air to be purged from the system, which will cause the overheating you see, and the low heater output. Make sure its clear.

The coolant smell at the exhaust is an ominous sign. As others have said pressurize the cooling system and do a compression test.

[zonie77]

"Radiator" caps go bad so check or replace it.

The dealer can make you a key. You need the title for proof of ownership. I had it done on one I bought at auction.

Forget what they've told you. Do your own diagnostics.

The combustion byproduct test first and cyl pressure test. If the HG's start to leak it is usually intermittent in the beginning. They will leak under higher loads and be OK at idle and cruise. As the erode they leak more.

It may not be HG's but check them first before wasting time & money on other things.

[JasonA]

The car does not overheat (it will get a little warm, a little past half, then go back to wherre it should be), but it is only 40* here.

By the way, this is normal. The temperature gauge is really programmed to fool the driver into thinking the engine is at "proper" temperature, and it is. But what normally reads straight up can be anywhere from about 188*F to about 220*F. As the engine warms past that, and it will at idle without moving without the cooling fans on, the temperature will rise and the gauge will start to indicate that by moving off center. Shortly thereafter, at about 229*F, the cooling fans engage and cool the system back down. The gauge will immediately return to "center". The cooling fans will then disengage in the low 200s. And if you're still not moving, the cycle will slowly repeat.

These engines are fine up through 240-245*F. 250*F and hotter and you may have a problem. But under certain conditions (probably not in the winter), you can see upwards of 230*F+, and that's fine. The only time you'll likely see the gauge move off center is during the winter, when it's too cold for A/C (so the fans aren't running) and you're stopped, either in traffic or at a drive-thru. Normally, the A/C is on and the fans are running and the engine won't even warm up to 220*F.

[clarkz71]

So there's no coolant running through the intake, or even the throttle-body to cool the EGR?

No.

Ranger, coolant DOES go through the throttle body on my 95, The purge line comes off the water crossover hollow bolt, goes to the throttle body, exits the throttle body and then goes to the surge tank. wiplash, I would re-check yours for that set-up. Although I've never heard of one leaking it would be easy to check. Just remove your MAF as you would to clean the throttle body. Then pressure test the system.

[WarrenJ]

Car is steaming coolant out the tailpipes, not much but enough to know it's there,

Why the discussion? Is there anyone who doesn't know what's wrong?

[Ranger]

So there's no coolant running through the intake, or even the throttle-body to cool the EGR?

No.

Ranger, coolant DOES go through the throttle body on my 95, The purge line comes off the water crossover hollow bolt, goes to the throttle body, exits the throttle body and then goes to the surge tank. wiplash, I would re-check yours for that set-up. Although I've never heard of one leaking it would be easy to check. Just remove your MAF as you would to clean the throttle body. Then pressure test the system.

Arrrg, sorry, I didn't read past intake.

[JasonA]

Car is steaming coolant out the tailpipes, not much but enough to know it's there,

Why the discussion? Is there anyone who doesn't know what's wrong?

I wouldn't consider that a scientific diagnosis. It can possibly be mistaken for something else, and I believe the original poster said that it only steams coolant when cool. I would think a traditional head gasket failure would be the other way around (steaming when hot).

In fact, the original poster did say a pressure test was done, and all cylinders held pressure good. Seems the head gasket checks out good.

[Regis]

Car is steaming coolant out the tailpipes, not much but enough to know it's there,

Why the discussion? Is there anyone who doesn't know what's wrong?

I wouldn't consider that a scientific diagnosis. It can possibly be mistaken for something else, and I believe the original poster said that it only steams coolant when cool. I would think a traditional head gasket failure would be the other way around (steaming when hot).

In fact, the original poster did say a pressure test was done, and all cylinders held pressure good. Seems the head gasket checks out good.

The information that is highlighted is what is troubling.

I just picked up a '98 Seville STS with 176k on it for $1800. The dealership selling it said the intake was cracked or leaking into the combustion chamber (via the intake runner in the head). I talked with his mechanic who diagnosed it to see how he ruled out a head gasket and here's what he said;

He did a hydrocarbon test on the coolant and caem up with 40ppm, he said typical HG failures show 2500+ ppm.

He pressurized each cylinder with 120psi and each one held.

That's all I know from him, which is all hear-say. Here is what I know;

There are no bubbles coming up into the surge tank,

The car does not overheat (it will get a little warm, a little past half, then go back to wherre it should be), but it is only 40* here.

Car is steaming coolant out the tailpipes, not much but enough to know it's there,

It runs rough upon startup, for maybe 10 seconds then it's good.

There's a check engine light on, which I'll check on Monday to see what it is.

There's no heat in the car, it seems as though the coolant system isn't under a lot of pressure, definately not 16psi.

Thanks for your help guys.

[WarrenJ]

In fact, the original poster did say a pressure test was done, and all cylinders held pressure good. Seems the head gasket checks out good.

NO . . . . he said someone (dealer mechanic) "told him" those tests had been done.

Regards,

Warren

[WarrenJ]

Without regard to who did what to which, if coolant is present in the exhaust there is only one conclusion . . . . and it's not a pretty one.

I don't care if it happens when the engine is cold or when it's hot. That it happens at all is a worry.

Regards,

Warren

[BodybyFisher]

I may be wrong but I think the coolant going through the TB is to prevent icing in the winter.

I have even seen recommendations to by-pass this feature by disconnecting the two hoses and attaching them together with a pipe and clamps to have cooler intake air (especially good in the hot weather)

[clarkz71]

That's correct. Helps cold drivability in general.

[wiplash]

Without regard to who did what to which, if coolant is present in the exhaust there is only one conclusion . . . . and it's not a pretty one.

I don't care if it happens when the engine is cold or when it's hot. That it happens at all is a worry.

Regards,

Warren

Well, I THOUGHT it was coolant, and think I convinced myself that it (the steam) was. It's about 18* here after the sun goes down and cooler in the morning so condensation is normal like you said. The other day I held my hand about 1/2" off the tailpipe so the condensation would collect then I tasted it, it definately is NOT coolant. (Sorry if I'm driving you crazy going back and forth on that one! ).

So now I'm left with no flow to the heater core (supply/return to the heater core are luke warm if that), and rough on startup, intermittent miss when warm.

Flow through the radiator seems to be sufficient as does system pressure (maybe a little low). What concerns me is the car came from the factory with Dex-cool and now it has the green stuff in it, which is fine if they did a proper flush, but I've heard it doesn't mix well.

Plug wires look brand new and do not arc in the dark. The car has a brand new FPR which isn't leaking. Both of those issues made my '95 Aurora run rough, but doesn't appear to be an issue on this car.

SO I'll have to get off my *smurf* and get the codes, can you do that from the DIC? And as far as the heater core issue I don't know what the next step would be.

Is my speed limited to 90mph because the "service suspension sys" is in the DIC? The struts are worn, how much will those set me back?

Thanks for your patience guys!

[BodybyFisher]

Run your CODES and post them here, you may have a simple disconnection at the strut or ABS that will cause the car to default to a lower speed for safety reasons.

You can find how to read the codes here:

http://www.caddyinfo.com/readingcodes.html

[JimD]

....

SO I'll have to get off my *smurf* and get the codes, can you do that from the DIC? And as far as the heater core issue I don't know what the next step would be.

Is my speed limited to 90mph because the "service suspension sys" is in the DIC? The struts are worn, how much will those set me back?

Thanks for your patience guys!

Here is how to read the codes http://caddyinfo.com/readingcodes.html

You will have a few "C" codes related to suspension.

You will likely have a quite a few codes if they have not been cleared for quite a while. I recommend clearing them all and doing a test drive, then reading the codes again. Have a Big Chief tablet and a crayola handy.

[Ranger]

So now I'm left with no flow to the heater core (supply/return to the heater core are luke warm if that), and rough on startup, intermittent miss when warm.

Check the purge line to be sure it is clear and flowing. If ok, then flush the core.