: $575 99 Seville project Car overheating



browe
11-14-11, 01:29 PM
I normally don't post threads but I am at a stand still on a N* in the 99 SLS
I purchased this car as a project car, with the knowledge that it had a blown HG

The first thing I did was do a Cylinder leak down test, and it identified Cylinder 1,3 as having issues. I also did a combustion leak test with the blue liquid at the overflow tank and it showed yellow positive

So I realize that the engine will need to be drooped and rebuilt sooner or later, but I decided to try a bottle of the snake oil (nanotechnology). Yes I can here the critics coming but I my goal is to get it to run enough to pass inspection...(overheating at the inspection station isn't good, plus its an experiment)

I made 2 attempts with the stuff
1st pulled no plugs, followed directions ,and didn't eliminate the gases bubbling through the overflow tank
2nd removed cylinder 1,3 plugs, disabled fuel injection to cylinders by removing power to the injectors, it made a horrible racket. Followed the directions flushed and filled with coolant....did combustion leak test and showed negative..

After combustion test testing negative and idling 15 or so minutes gas would build up in the cooling system, pushing coolant out the purge tank...I checked the coolant purge line on the crossover and it was logged with corrosion. I used a 1/16 drill bit to remove the corrosion on the aluminum fitting and have a good stream through the overflow (roughly flowing 1pt per min)....and can see air properly purging from the system when running

So now I still see gas build up in the system after 30-45 min idle only after the engine gets above 220 deg….combustion test is negative at that point . At least until the coolant gets to the top of the overflow tank. Another symptom is that the heat quits working when this happens…ie a gas bubble in heater core?

What other possible sources of air introduction in to the cooling system (other than HG) are there?


Thanks in advance for the input

Ranger
11-14-11, 02:47 PM
Another symptom is that the heat quits working when this happens…ie a gas bubble in heater core?

Yup.

Sounds to me like you have confirmed that it is a blown HG. Snake oil seldom works and you seem to have confirmed that.

tateos
11-14-11, 09:32 PM
With the N* HG problem, the the reason the heater stops working is because combustion gases have entered the cooling system and displaced coolant that should be in circulating in, among other places, the heater core.

browe
11-16-11, 12:54 PM
thanks

I guess the negative test for combustion gasses in the over flow tank must be due to the coolant scrubbing the hydrocarbons out of the system?

Ranger
11-16-11, 03:30 PM
Yup. Exhaust gases get vented to the surge tank via the purge line.

tateos
11-17-11, 06:03 PM
Most people that have the HG problem go through a period of denial - they do test after test, then replace this thing and that (thermostat, radiator, temp sensor, water pump, fans....) out of disbelief that the HGs can actually be real problem, but it is almost invariably the HGs. The cars have a pretty stout cooling system, so we almost never hear of overheating that wasn't the HGs.

drewsdeville
11-18-11, 08:55 AM
Keep us updated on the project. Craigslist is riddled with HG Cadillac victims selling for cheap, and I've debated pulling the trigger on one numerous times.

browe
11-23-11, 12:26 PM
I most probably will go to P & P this weekend to get a LD8 northstar. in a 99 Deville .they have a 50% off all in the yard sale...so cost would be $95 with core..dirt cheap...I like to have a 2nd engine to rebuild (winter project) then swap with the one removed ...plus it helps with bolts and sensors and accessory...but I am a little leary on getting an engine that I dont know how it runs.

Has the N* seen much bottom end issues....rod or main bearings, oil pump? I just got done with a Chrysler 2.7 in a 2001 sebring convertible....challenging timing chain, rod and main bearing issues...but that's why it only cost $1000..The boss loves to drive it!!!!!!!!!

Submariner409
11-23-11, 03:45 PM
A Northstar engine that appears clean and dry, head gasket failure notwithstanding, should be a good top overhaul candidate. If the oil pan seal and the halfcase seal are weeping oil, either walk or know that head gaskets are only the beginning. The crank, lower end and oil pump are stout and reliable. Know that the proper torque procedure is MANDATORY for the harmonic balancer: The oil pump is driven by clamping friction between the balancer hub and a crankshaft shoulder - guess at the procedure and you have no oil pressure - none.

Subscribe the car to www.alldatadiy.com and do some top overhaul homework - it will be necessary.

Take a long look at www.northstarperformance.com and/or www.huhnsolutions.com

89falcon
11-23-11, 03:57 PM
I most probably will go to P & P this weekend to get a LD8 northstar. in a 99 Deville .they have a 50% off all in the yard sale...so cost would be $95 with core..dirt cheap...I like to have a 2nd engine to rebuild (winter project) then swap with the one removed ...plus it helps with bolts and sensors and accessory...but I am a little leary on getting an engine that I dont know how it runs.

Has the N* seen much bottom end issues....rod or main bearings, oil pump? I just got done with a Chrysler 2.7 in a 2001 sebring convertible....challenging timing chain, rod and main bearing issues...but that's why it only cost $1000..The boss loves to drive it!!!!!!!!!

If you swap with an SLS engine, you REALLY need to swap the intake cams at the same time....that's the main difference between the two engines....and possibly oil cooler ports on the oil filter mount....if so, swap that also.

now think about this.......why would a 12 year old cadillac be in the junk yard? If it were a low mileage car that got totaled a couple blocks from the dealership, the engine would be LONG gone. If you are lucky...and I mean VERY lucky, the junked it for a bad suspension....also a very expensive fix.....or possible a collision.

The bottom end is "stout". I wouldn't lose much sleep about it....and hopefully the car that was $45K off the lot 12 years ago, was well maintained....but unless you "know" it was running great without overheating (I've seen a lot of people blame the "cooling system" for the problems instead of the HGs....it IS the HGs), I'd give a lot of thought to fixing the HGs in a pre-emptive move......and fix the bottom end oil leaks at the same time.....but DON'T touch the rod bearings, and only inspect the mains when you split the block to fix the oil leaks......about $1000 in parts is worth it to me to know I won't be pulling the engine again in the next 100K miles.....

I swapped a 97 SLS engine into my 97 STS. My kids have beaten the car to death (colorado winters....I feel VERY comfortable with them driving the tank with stabilitrak!)....so the car itself wouldn't be worth much even with a brand new engine.....so I took the chance on an engine I was told "ran great and didn't overheat".....about 5K miles and 5 months into it...so far so good (my kid's school is about 3 miles away). My original engine had over 200K miles, and the bearings look really good when I disassembled it. I only wanted to get 1-2 more years out of the car.....otherwise.....fix it before installation.

Submariner409
11-23-11, 04:13 PM
If you swap with an SLS engine, you REALLY need to swap the intake cams at the same time....that's the main difference between the two engines....and possibly oil cooler ports on the oil filter mount....if so, swap that also.

He has an SLS (VIN Y engine, LD8) and is trying another identical engine, so there is no need to swap cams UNLESS the cam lobes and cam follower buckets are worn/dished.

If the original vehicle was not equipped with the HD Cooling RPO (and almost no SLS was) there's no need to look for an oil filter adapter with the oil cooler line quick connect fittings.

89falcon
11-23-11, 08:19 PM
Ahhh....for some reason I thought he had an STS...:thumbsup:

maeng9981
11-23-11, 11:52 PM
$95 for a spare Northstar? That's a steal!

89falcon
11-24-11, 11:34 AM
$95 for a spare Northstar? That's a steal!

There might be that much in aluminum in it....

browe
12-06-11, 03:10 PM
Picked up the 97 LD8 long block from a 97 De ville Base on Black Friday $124 inc core ( I figure at least 250 lbs scrap aluminum if all goes south.. what a bargain!!!! .besides it gave me good practice on dropping the carriage, accessory disconnection and 6 bolts, and on the ground. man that was easy...It was More difficult separating the tranny from the block...

accessory's were already picked but I dont in intend to use them since I will be using tall other acc from the 99 LD8

I think I may be lucky, the car had damage, flipped over, top bashed in and mangled on one side. On removal of the carriage I saw the tranny had a huge crack on the side of the cast housing....engine may be good

With all the my other projects, helping the boss with x-mas decorations, I haven't had the chance to get the engine on the stand to do a through inspection. I did attempt to remove the torque converter bolts, with a 1/2 impact wrench...wont budge...I will be using 3/4 impact next with a propane torch to heat up the bold to break the locktite....(may be virgin)

I have been looking at gasket sets
the head set is the same for 95-99 LD8
But the conversion set is different PN for the 97 and 99 LD8s
I know the 99 has liq cooled alt while I assume the 97 is air cooled, correct?
The last 6 of the VIN for the 97 Deville is 296923....(what was the 97 production of Deville's?)

What other differences would contribute to the 2 different conversion gasket sets?

Thanks!

Submariner409
12-06-11, 04:31 PM
Did you wade through the sticky post on engine swap differences - about 8 threads up ^^^

browe
12-14-11, 01:31 PM
Got the engine on the stand
Before digging in to it I decided to run a couple of tests, compression and leak down loss

Cy psi % loss

1 180... 55
3 120... 55
5 100... 75
7 140... 55

2 180... 50
4 90.... 70
6 180... 50
8 125... 50

After review it was time to tear in to the engine
I pulled all head bolts and found 1 that has aluminum threads stripped, intake between cyl 6,8
Gaskets didn't look too good either

All other bolts have no striped threads

QUESTION:

1. if the threads have been serted previously will the sert remove out with the bolt? How do I confirm that the block has no serts, hole diameter?

2. Crank has a couple of dots that match with timing marks, so I assume that the engine has been worked on previously. To confirm Color of crank rear seal is green, what was GMs OEM seal color?

Ranger
12-14-11, 02:56 PM
1. if the threads have been serted previously will the sert remove out with the bolt? How do I confirm that the block has no serts, hole diameter?

The insert should stay in place when the head bolt is removed and once the head is removed you should see the top of the insert (opposite end of the circle) flush with the block deck surface .

http://www.timesert.com/images/index/image003.gif

ternstes
12-15-11, 07:30 AM
GM oem rear seals are green, but that doesn't mean others aren't as well. If it's a gm seal, it will have GM's part number stamped on it. Fel-pro's seal is blue I believe, though.

Mark C
12-15-11, 04:32 PM
Timeserts are not flush with the deck they are about 1/2" down in the hole. The drill that installs them is countersunk, so if the bolt hole is a larger diameter than the head bolt shaft, and you can see a small horizontal lip (maybe 1/32" wide) down in the hole its been "serted" before. The Timeserts are installed with red threadlock on the exterior threads, and the installation tool also compresses the threads a bit to get them to seal tightly to the block. They won't comeout unless the block was incorrectly machined (drilled) for them.

There is a difference in oil filter housings between a car with the external oil cooler and one without, you can not just add the oil cooler lines to an adapter that did not have them originally. GM has 2 different part numbers for the two different styles of adapters, and of course the one with the external oil cooler is no longer serviced. I beleive the only difference is the presence of a releif valve between the inlet from the oil filter, and the outlet to the block in a car with the oil cooler. The releif valve is normally closed and forces oil to go to the cooler, but if one of the lines gets plugged or kinked, it will open and send oil directly to the block. A car without the oil cooler would not need that releif valve since the oil has no where else to go except out the outlet port and into the engine.

Submariner409
12-15-11, 06:58 PM
He's not talking about an oil cooler - he's fooling with the water cooled alternator that was a Cadillac bugaboo for a year or so. Post #10 & #11.

The oil cooler bypass is used to allow block lubrication as the oil warms - the cold oil does not want to circulate through the radiator tank "cooler" and then go back to the filter proper ......... oil filters themselves use internal bypasses because practically NO OIL passes through the filter media until the oil gets quite warm. Internal bypasses lift at 10 - 15 psi: under high viscosity (cold oil) or high flow (upper engine rpm) conditions a significant amount of lube oil is bypassed straight to the block passages. The Northstar oil pump has an internal discharge pressure regulator/bypass which dumps excess discharge oil back to the intake side of the pump.

Are all Timeserts deeply countersunk or only the 4 that have the head locating dowels inserted on top ?

Ranger
12-15-11, 11:54 PM
Timeserts are not flush with the deck they are about 1/2" down in the hole. The drill that installs them is countersunk, so if the bolt hole is a larger diameter than the head bolt shaft, and you can see a small horizontal lip (maybe 1/32" wide) down in the hole its been "serted" before.
I stand corrected. My only point was that that once the heads are off, it should be obvious whether it has inserts or not.

Mark C
12-16-11, 03:37 PM
All of them are countersunk, but I think the 4 that have the alignment dowels already had a larger hole for the first 1/2" or so, so that the head bolt could pass thru the center of them originally. You can reuse existing (if you don't F them up getting them out), or use new dowels after timeserting a block so the new hole that you drill for timeserts is still not as large as those 2 holes per head where the dowels go.