Northstar Engines and System Technical Discussion Discussion, *98 Deville- Coolant in Oil? in Cadillac Engine Technical Discussion; Hello,
We took the '98 Deville in to our mechanic because there was coolant all over the top pf the ...
We took the '98 Deville in to our mechanic because there was coolant all over the top pf the engine and it was "burning", the coolant and not the engine). (I posted about a bizarre coolant loss/ a/c problem before.) they replaced a hose that was supposed to have been leaking , I tentatively asked whether there was a head gasket problem -they said no, the car ran fine for a few weeks, even the A/C was working properly again. Now this...
The car started needing coolant every couple of days and shaking violently when started again, then one day it started overheating and even cut out, my husband noticed that the oil light was now on in conjunction with the check coolant level light, even after he added coolant. (This all appened within 20 minutes). He says that the oil looks overly full and I am concerned hat there is coolant in the engine, although this is not certain. At the same time I understand that this is nearly impossible with a Northstar engine.
Any other possibilities except oil cooler or head gaskets or how to diagnose the above?
The symptoms you describe could be associated with head gasket failure all right, but they are not conclusive. Head gasket failure may present with several different symptoms, depending on where the breach occured on the gasket. You can check for water (coolant) in the oil very quickly by examning the engine oil dipstick and the oil filler cap. There will be a thick, yellow or white sludge present on the bottom of the filler cap and/or the dipstick if coolant is reaching the engine oil. Also, allow the car to set for 24 hours without running the engine. Then remove the oil drain plug and take note of what comes out, initially. Water is heavier than oil and it will settle to the bottom of the oil pan overnight.
If an oil cooler rupture is suspect, check for oil in the coolant. Whenever the engine is running, oil pressure is much greater than the coolant pressure, and the oil ends up in the coolant. Only when the engine is warmed up to operating temperature and then shut down does the situation reverse, with the coolant pressure becomming greater than the oil pressure. If the two liquids are communicating within the oil cooler, oil will be floating on top of the coolant in the radiator or in the coolant recovery tank.
I checked (except the oil pan)and didn't find any of the symptoms that you described above. The check engine light is now staying on. The oil dipstick is well over max, I understand that this is not good. but at the same time the 0% oil life indicator is consistent with a 3k mile change. (I understand that the car is not smart enough to give this message of its own volition). I even looked in the coolant reservoir and saw no "bubbling". The oil was opaque but not thick, I supppose that this is consistent with needing changed rathr than the "chocolate milk" of gasket failure.
I understand that on the day of the "crisis" there was smoke/steam coming from the engine and it was overheating, unusual for a Northstar? an definitely unsusal for our car, despite the coolant trouble., we still don't know where the coolant is going, it doesn't appear under the car. I suppose it is being burned off. One mechanic changed the coolant cap, a second, who I trust, changed a hose, the first one claimed to have pressure tested the system and found no leaks. ) unless we have discovered a wormhole to another dimension in the coolant tank or reservoir!)
I wait to hear the diagnosis tommorow, holding out hope for something other than gasket failure,
As you mentioned in the first post, the N* doesn't put coolant in the water until the headgaskets are almost gone. It's just how the engine was designed.
But you say your oil is overfull...so I'd have to think it's either coolant, or a stuck open injector putting excess gas into the oil. Does the oil smell like gas? That could be the rough running. It's odd you'd have a ck oil light with the crankcase full.
It would be a good idea to get the oil changed right away to really see what you have. Take a look at it when it is drained.
A compression test (at the minimum) or preferably a cyl pressure test is in order.
I have taken an interest in your situation Avokshi, and read all your posts concerning the problem. And after making a list of all the symptoms you described and reviewing them, my diagnosis is...HEAD GASKET(S)! *lol* Sorry, but that's what it sounds like to me. When mine failed, I lost coolant into the valley of the engine, which drained down and out on the road. It only occurred when the car was running down the road, so it was hard to detect. I could not duplicate those conditions in the shop and get it to leak.
The A/C system cuts out when the PCM detects low coolant or high engine temp.
in order to conserve engine power. The N* is a funny bird - it doesn't always react the way typical engines do when problems occur. For example, my engine showed no loss of compression when my head gasket failed. Compression tests showed 185 lbs. on all cylinders. Go figure! *lol* I had no coolant in the oil either. Two classic signs of head gasket failure which were not present at all! Bottom line is, you have replaced the cap with one that you know is good (tested, I presume), you are not losing coolant through the heater core which would be leaking into the passenger compartment, you have fixed all the external leaks, the coolant loss precedes the overheating and you are not getting oil into the cooling system. So what else could it be?
The violent shaking at start-up is probably water in the cylinders trying to compress, and the rise in oil level is the coolant going into the pan. The steam comes from coolant leaking out on to the engine, probably into the Vee of the engine block, as mine did. I could see "high water marks" in the valley upon teardown that indicated as much as three inches of liquid was filling up the vee, then slowly draining back out onto the ground. I never did see a leak out the bottom of the car when I looked underneath. Diagnosing N* head gasket failure is often confirmed by simply eliminating all other possible causes, as it was in my case. I had my radiator reworked, replaced the thermostat, the water pump, the cap, flushed it out...and still it overheated and blew the coolant out.
Someone suggested a stuck injector putting fuel into the crankcase, and that is certainly a possibility that might cause several of the symptoms you describe. But I think if that were true, you would notice that the first time you pulled the dipstick and all the oil ran off it because the oil is so thinned out. And you would smell gas instantly too. Just for curiosity, why don't you pull the oil drain plug and see what comes out first? I'll bet it's coolant!
The car is in the shop as we speak, I will ask "what" came out in the pan. After I checked the dashboard myself, the oil light is not on just a message saying 0% oil life left. The oil did not smell gassy, I do not think that it was thin either.
We have abut 76,000 miles at present, Powerglide.
I am asking for an oil change and am having the system flushed and replaced with Dexcool, as well as of course troubleshooting the leakage.
I really really hope that it isn't the Head gasket, keep you posted...
"The A/C system cuts out when the PCM detects low coolant or high engine temp."
Would this cause the cooling fans to act up... During my driving with bad gaskets the fans would cut out. I could get them to come back on by turning on/off the AC and reseting the computer while driving...
I'm no authority on the subject, but the cooling fans typically come on at start up for a minute or so, then kick off. They don't come back on again until engine temp reaches 235-240. I don't know how you were able to engage the fans by clearing the DTCs, but that's a neat trick! *lol*
I did this because I took the car in to the dealer cause the fans were not working. They cleared the codes and they worked for about 20 miles before they stoped working and overheating the car. @ $100 for 20 miles I figured I would clear them myself. But they would only work for a few miles or so when I clear them.
Yes, according to our local mechanic, definitely head gaskets and they don't want to touch the N* so we left the car at a dealer. Discovered that the car was certified untill 5k miles ago- interesting, no tsure exactly what this means and hence had a pile of work done in the past. HVAC, A/C new Radiator and more. They don't know exactly but were saying 30 hours labor, is this true?
Avokshi, if they can pull the engine, timesert it and reinstall it in 30 hrs. they are doing good. That is a fair price indeed if their labor rate is < $60/hr. By the time you add tax and all the extras, I'm sure your bill will be well over $2K before you are out the door with it. And sadly, that's only a "wham, bam, thank you ma'am" job. I doubt they will even look at things like head warpage or valve seating. As I said before, both had to be addressed on my engine while it was apart. Seems like an extraordinary amount of money until you consider that the N* is 250K mile engine when properly maintained. The headbolt thread weakness is unfortunate, but once you get past that you should have an engine that will out-last the car. I wish you lived a little closer to me - I could probably save you some money on the labor! *lol*
MightyBright1, your fans shouldn't be coming on during routine driving in Spring time weather. You must be running hot. The fans only kick on when the engine is way hot, as a means of bringing that engine heat back down to an acceptable level. You should be at 206-216 degrees if everything is ok with the cooling system.
They were "ballparking" $3k labour and $200 parts, However they are inspecting the vehicle themselves this morning. We are also getting a GoodWrench inspection, hopefully that won't turn anything else up. Looking at that the labor rate is more like $94, probably cheaper to hire an attorney...
Yes, reading the high mileage thread on this forum definitely eased my mind about making this decision, also it made me suspect that our 1980 Eldorado (currently showing at 40k miles, may have been around the odometer a fair few times.
I wish indeed that you were local, or better yet, to be a mechanic myself
I wonder if this was a cooling system issue, maybe the coolant was never replaced or did not have the sealant in it. But then again, you did mention that the radiator had been replaced under warranty--presumably the car had an overheating history (telltale sign headgaskets were weakened).
Mechanix, what about in your case? Why do you attribute the failure?
My understanding, from reading other postings on here, is that the headgasket job is not too common--and almost always due to cooling system failures, and other times from neglecting the system or not adding the sealant. We read about it so much because it's usually frustrated owners that find somewhere to vent. The happy ones usually don't find somewhere to complain--because they don't have any complaints.
As a matter of fact, I was very aware of the sealant when I had my car inspected prior to purchase--so I was asking all sorts of questions about the sealant. They looked at me like I was crazy. "You only need the sealant if you have a leak." I never went back to that place. As soon as I purchased it, I drained and re-filled the cooling system, as well as added the sealant to the hose (2 tubes of barsleak powder).
Mechanix, I have a warranty, but if I ever have the headgasket problem--I'll ship my car to you and spend a weekend assisting you in fixing it. I've seen you offer help before, and you have experience doing it. I'm closeby too (north Texas); however, I hope never to have that problem with good preventive maintenance, and never letting the car overheat if I can help it.
Save yourself $1000.00 and find a reputible mechanic to do the work. Had mine done with head resurfacing for $2200 - Had to use the "bigserts" beacause of a helicoil job that was done previously and finially failed. Dealerships are way too pricey.