How does this happen? - GM Performance Tuning

Beginner · #1 (**permalink**) 02-15-2007, 07:10 AM

Hi all,

I have a 99 Deville with the Northstar engine (4.6L). To make a long story short, my Mass Airflow Sensor was damaged by a Cadillac dealer Vienna VA. This lead to the vehicle racing. The racing led to the engine overheating and spewing antifreeze from the engine. The overheating happend just as I started enter into the local garage. The Mass Airflow Sensor was replaced. Not being car smart, I had no idea of what would or could happen.

The engine started to leak water. It appeared to be from the reserve tank and I thought nothing of it, just added the water. As time when on, the engine started to run very poorly. I had a friend come over and we changed the spark plugs and wires. At that time, my friend said that there was oil and anti-freeze, and possibly water on the spark plugs. I asked if that could be related to the situation I had. He stated that he is not a mechanic and if this fixed it and the vehicle started to run poorly again, that he would take it in and have it checked out. The vehicle ran great after the change of plugs. About a month later it started to run poorly again and I brought it in to be checked. It turns out that the head gaskets were broken. I am told by others that this would have happened when the engine overheated. GM and a cadillac dealship say that it "could" have happened then, but there is no proof.

Thinks went back and forth and when I finnally brought the vehicle in be repaired I was told that I needed a new engine. Apparently the bearings are bad. This was determined because the mechanic heard noise from the bottom of the engine and from experience they 'know' that it needs a new engine. Asked how this could happen I was told that the oil was thin. Asked how that could happen and was told that water could have been thinned it (paraphrased). Ask if it could be related to the busted head gaskets and was told that it 'could'.

My question is how could this have happened? After doing some research on the engine, it appears that there is a feature that when the engine gets hot, it will shut down up to half of the engine to allow airflow to keep the engine cool. This is suppose to work up to 50 mins or so. I drove no more than about 15 mins. The engine became so hot from racing that it cracked the water reserve and spewed out the antifreeze. I would take the belief that the engine was extreamly hot for the safe gaurd to be bypassed like that. This in turn would have busted the head gaskets. This in turn would have allowed water to enter places it should not be. This in turn would allow the engine to be destroyed.

Could anyone out there tell me how or what the logical sequence would be for this to happen?

Any help would be most helpful.

Craig

jamz · #2 (**permalink**) 02-15-2007, 09:10 AM

Hello .. Vienna, VA huh? I worked 4 years in the auto industry in Vienna and northern va in general (doing IT stuff, etc.). I'm not to sure what the logical sequence would be, however, I'm sure someone on the boards will have a bit more input and reply .. Glad to have you on the site.

Beginner · #3 (**permalink**) 02-15-2007, 08:12 PM

Jason,

Thank you. So far everything has been very nice. Yes, I hope that someone here will be able to help me.

Craig

Nels996 · #4 (**permalink**) 02-15-2007, 09:40 PM

I'm new to this board but not new to Northstar Engines. I'm a service technician that works on them. I had a few NS that leak coolant through the head gaskets. I suspect cylinder 1 or cylinder 2 had indications of coolant in them. If that's the case both those cylinders are the closest to the timing chain area. A small crack develops in the gasket and leaks into the cylinder and into the timing chain area. There is a coolant opening that feeds the cylinder heads between the cylinder and the timing chain area. The timing chain is lubricated by the engine oil, intern why you have coolant in the oil as well as the cylinder. If you ran the engine long enough with coolant in the oil you will damage the engine. I would get a second opinion.

Formula92 · #5 (**permalink**) 02-15-2007, 10:36 PM

Wow, that was so interesting to read even though I don't deal with those engines. I'm a service technician as well, but unfortunately on VW. Yeah I know, I hate the damn things, but they offered me more $$$ than GM, so I took the job. I've been working on cars since I was about 16 though, and I currently own a 1992 Firebird Formula and a 1981 Camaro, both V8s. But, before I start babbling on about my rides and spec's, I just wanted to say that you really know your stuff Nels, and sorry to hear about your problems Craig.

Beginner · #6 (**permalink**) 02-16-2007, 03:36 PM

Thank you all for your responses.

Nels996 - I am not sure if the cylinders had any indications of collant in them. I was told they did a chemical test to find out if the head gaskets were busted. They stated that they knew at last one was busted. I did have, at one time, oil in my antifreeze. I asked a mechanic friend of mine what should I do? He said to get it fixed. He then told me that I could get GM's coolant tabs and put them in the coolant and they 'should' seal the leak. This would not fix it, just seal it. I did that and that appeared to work. I have not seen any oil in my antifreeze since then.

When I brought the vehicle in to have the head gasket's replaced they told me that both were busted and that I needed a new engine - a short block and $1100 worth of parts. The total was going to be a little more than $8,000. I asked how they knew that it needed a new engine, they heard noise from the bottom of the motor and their 'experience' told them. They stated that it was the bearings. I said ok. They also stated that there was not a 'milkshake'. I'm not exactly sure what that is - a mixture of antifreeze and oil? If that is what it is, then the coolant tabs are really working. I had changed oil, using mobile 1 again, after putting the coolant tabs in, just to get anything out of the oil to stop any further damage other than the gaskets.

So if I understand you correctly, the following is most likely what happened:
1.) the Mass Airflow Sensor broke..... which
2.) made the engine race..... which
3.) made the engine over heat..... which
4.) busted the head gaskets..... which
5.) allowed water or antifreeze into the cylinders.... which
6.) would allow water or antifreeze into the time chain area.... which
6.) would destroy the engine - specifically the bearings?.

If the water or antifreeze got into the time chain area, would that make the bearings also be destroyed or since water or antifreeze got into the timing chain area, everything would be destroyed?

I hope I have this pretty much correct. Please help where I went off. You have been most helpful so far and I really, really appreciate it.

Craig

jamz · #7 (**permalink**) 02-16-2007, 05:47 PM

Great info for sure .. thanks nels!

Nels996 · #8 (**permalink**) 02-16-2007, 08:43 PM

I haven’t experienced a high idle condition caused by a MAF sensor. I can’t see how that would cause the engine to over heat. As long there was sufficient coolant in the cooling system it should have been fine. Are you sure it wasn’t a vacuum leak? Was your cooling system low on coolant? Are you the original owner of the car? Did the engine over heat before? Do you have any repair history on the car? Where the head gaskets develop the crack it’s between the two front cylinders and the timing chain area. With the coolant leaking into the timing chain area it will mix with your engine oil. The timing chain system is lubricated by engine oil. If you have coolant mix with your oil long enough it will damage the bottom end.

Beginner · #9 (**permalink**) 02-16-2007, 09:23 PM

Nels996,
What happen was the MAF sensor was damaged while at the dealership. Within 5 mins of leaving the dealership the vehicle started to race. I checked the Cruise control and that was off. Checked it several times. I tried slam braking it and the vehicle still speeded up. I tried flooring it and that did not work. When I brought it to the local repair shop, the vehicle was spewing out antifreeze. When the hood was open, the MAF sensor was ripped open. There is a seal that apparently holds the MAF to the engine. That seal was caught in the in the MAF. There appeared to some type of 'flap' that gets opened, apparently to let in air. (I don't know, just guessing). The seal kept this 'flap' from closing. When the MAF was replaced the vechicle ran great - for awhile.

On the vacuum leak - there was not one that I know of. The vehicle was running perfectly. I needed a battery replaced so I brought it back to the dealership to have it replaced. When I left, this all happened. I suppose there was a BIG vacuum leak when the MAF sensor broke. I mean this whole was big.

The system was full of coolant.

I am the original owner of the vehicle.

After 3 years, I had the vehicle certified. I was going to keep this GM vechile longer than I kept the other one - 76 Olds, kept it for 22,23 years.

The vehicle never over heated prior to this one time. Since it started to spew antifreeze it really must have been hot to by pass the 'limp home' feature.

I have the complete repair history. Nothing major was ever wrong with the vehcile.

I do not know where the head gaskets were busted. I am not sure that the dealership knows either. They just put some chemical in the engine to test if they were busted or not. They did not actually break down the motor.

I only saw oil in the coolant once - about 3 months or so after the MAF situation. When noticed, I add the coolant tabs and never saw oil in the coolant again.

Does that help you any?

Thank you so much for trying to help me. This has been a complete mystery to me; and I do not get complete answers from the new dealership that I take it to. All they tell me is that it 'could' all be related to the destruction of the MAF, but there is no way to prove it. I am just trying to figure out what mostly happened. I thought we were getting close until you told me that you have never heard of that happening.

Nels996 · #10 (**permalink**) 02-17-2007, 01:07 PM

Yes it does help. With the repair history known there is a good chance you won't need an entire engine. Again this is only based on the info that's given to me, as well not testing the car myself. I come across this often. There aren't a lot of techs/shops that know or want to repair the NS engines. So they can't give you a direct answer. If you can find some one that knows how to diagnose the engine properly. There is a good chance you would only need to have the head gaskets replaced, as well have the heads tested. I hope this helps you.

Nels996 · #11 (**permalink**) 02-17-2007, 02:43 PM

Quote:

Originally Posted by Formula92

Wow, that was so interesting to read even though I don't deal with those engines. I'm a service technician as well, but unfortunately on VW. Yeah I know, I hate the damn things, but they offered me more $$$ than GM, so I took the job. I've been working on cars since I was about 16 though, and I currently own a 1992 Firebird Formula and a 1981 Camaro, both V8s. But, before I start babbling on about my rides and spec's, I just wanted to say that you really know your stuff Nels, and sorry to hear about your problems Craig.

I'm sorry to here that you have to service VW's! I'm not to found of them myself. What do you do for fun with your Forumla? do you track any of your cars? I don't see any Formula's on the street or the track up here.

Beginner · #12 (**permalink**) 02-17-2007, 10:39 PM

Nels996,

Where do you work? I'm in VA. If you are not THAT far away, I would bring the vehicle to you to check it out. I gather that you take the belief that you can not really tell if the bearings are damaged just by hearing a noise at the bottom of the engine. If the cadillac place does not have the mechanics that can tell, what mechanic would be able to tell? Is there a specific test that can be performed?

Craig

Nels996 · #13 (**permalink**) 02-18-2007, 01:28 PM

Craig, I'm located in Toronto, Ontario. I wouldn't think the car would make it. But if it's something you want to consider let me know. There are tools and tests that can be performed to determine the noise that you here are either bottom end or top end.

Nels

Beginner · #14 (**permalink**) 02-18-2007, 01:57 PM

Nels996,

Ok, that is to far. What test would need to be performed to verify or ot find out what that noise is? I have have friend that has a lot of tools, so he 'may' be able to do them. I can't hear the noise on the bottom. The noise I hear sounds like it coming from the top of the engine. But I don't know for sure. Let me know what the test are and I'll go from there.

Again, thank you so much. You have truly been very helpful.

Craig

Nels996 · #15 (**permalink**) 02-18-2007, 03:56 PM

Craig,

You will need a sonic noise detector tool in order to pin point the noise. Does the noise have a deep tapping sound or a light tapping sound? It would be the same as a hammer tapping a piece of metal continuously or is it like the metal end of a screw driver tapping on piece of metal? This will help determine roughly where the noise is coming from.

Nels