Subject:

Typical 91 - 900s non turbo 2.1 liter motor.

This article details a 94 900s Convertible with 90848 miles on it.

Eroded block coolant passage that extends into cylinder #1 sealing surface at the metal ring of the head gasket that encircles the cylinder bore.

Basically what we have here is block damage. The usual and customary fix is to replace the motor. Back on 1/8/98 we had a 92 900s in for a head gasket job, major service, front brake pads and alternator bushings. We did all the other work and saved the head gasket for last. On removing the head, we found a very bad case of corrosion in the cooling system yet the antifreeze was very GREEN. That means no rust brown color as you would expect with corrosion. On cleaning the block and head surface, the erosion was very extensive. We resurfaced the head and went back with a new, updated, modified head gasket. On start up we had a immediate failure with combustion in the coolant system. we pulled the head off again and discovered a .014" gap in the demonstrated area. I knew as a shop owner that It was going to be bad news to the lady that owned this Saab and I felt for her.

Digging back into my 26 years experience at that time, I remembered when I was a kid working in a body shop and how I brazed many metal panels onto car bodies at the rocker panels that were rusted out and a friend that was ... well he had xray welding certifications from Kaiser steel, and Standard oil that were a foot thick. I helped Randy Ury weld a cast iron vice that was several generations old and the farmers son broke it. Randy showed me how to prep and deal with cast iron. Later on in life, I remember being at the machine shop, dropping off a axle and a farmer in there raising He.. It was the middle of harvest and the new head would have to come from England for the old tractor. The head was right under my nose on the counter and I kept looking at it ....Hummm. It wasn't my place and I didn't speak up ....but I always thought, man if I could have put the brass to it and had the machine shop deck it, that farmer would have supplied me with potatoes for a long time!

On this 92 900s, I thought about it and just did it. It was the end of the day and we walked away from it. The next morning I came in early with a new file and went to work on it. Several hours later it was perfect. My helper came in and freaked when he seen the results. My helper was a factory trained Saab Master Tech with enough special training certificates to fill the back of a pickup truck. He is also a ASE certified master.

Here is something that just caught my attention. This 92 had 90849 miles on it back in 1/8/98 when I did its head gasket / block repair and the 94 that this article is based on has 90848 miles on it. I last serviced the said 92 on 2/19/02 with 122783 miles on it and no indications of head gasket or block failure. This 94 was the seventh 2.1 that I performed this procedure on.

The Cause:

The cylinder bore was increased on the 2.1L motor and the distance between the indicated coolant passage and cylinder bore was decreased. I suspect that the antifreeze that came from the factory may have been weak or at past major services the system was not flushed or dealt with properly. As soon as combustion started entering the coolant, the PH level became very corrosive and started eroding away at the metal. I have also noticed the plastic in the heater valve where the heater hoses attach becomes very brittle and crumbles or snaps. The same goes for the heater bypass valve. The replacement head gasket was modified at the coolant passages, material and the ring size that encircles the cylinder bore. This can be noted in the attached pictures.

 

Some Research into the History and case study:

These are the documented 2.1 head gasket jobs I have done.

 

Case Study: ..................[Cooling system serviced]............[Head Gasket Total Failure]....................[Last Seen On]

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Tom Harmon .......................58540 on 2/5/99........................ 63426 on 8/25/99 ........................105851 on 8/24/01

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John Bryson ........................64658 on 11/7/96...................... 66538 on 12/30/96 ......................131814 on 8/29/01

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Judith Bobo .........................72251 on 2/12/98......................112667 on 8/22/01

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Curtis Elliot......................... 55469 on 6/13/96.......................74315 on 5/12/97.......................... 111477 on 6/7/99

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Frank Cashwell....................55721 on 9/21/99.......................77265 on 12/8/99.............................98070 on 10/3/01

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Dist Networks*...................69968 on 8/26/98........................84568 on 1/15/02............................85089 on 6/13/02

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Elizabeth Heard*..................64585 on 4/22/98........................90478 on 2/29/00............................113262 on 1/17/02

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Polly Ellsweig*...................90849 on 1/8/98.........................122783 on 2/19/02

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Ethan Bailey........................93485 on 1/23/98.......................138230 on 3/7/02

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David Wheeler*....................95650 on 11/3/99.......................115639 on 3/14/01............................129545 on 4/5/02

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Ron Hales*.........................124774 on 1/7/02........................126991 on 3/11/01

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Susan Walchman*................127442 on 2/6/02

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Townsend 91.......................135491 on 4/23/99......................139208 on 5/6/02

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Roger Hill*........................79675 on 3/14/00........................90848 on 6/4/02...............................Featured Article

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*= Block Repaired

The block damage is typical of the 2.1L and not as pronounced in any of the other Saab Motors. The variables are either the alloy the block is made from is different, the antifreeze was of poor quality originally or the service of the cooling system was poor. The 2.1 head gasket started with a very slow leak early in life and the combustion that entered the cooling system rapidly changed the PH level to a very corrosive nature. The early head gasket failure may be attributed to high temperature gauge readings because of the single radiator fan operation verses both fans on the 90 down 2.0L 900 and ALL turbo models. Most these cars had the relay and wire modification done at the cooling system service. I will also note that there was instructions from Saab to replace the time limiter relay for the radiator fans with a NON time limit standard relay. I have been eliminating them on all Saabs for a long time. The reason is its a expensive relay and will fail in one of two ways. It will stick and the fans will run till the battery is drained or WORST ... The radiator fans wont turn on at all when needed. After witnessing it a half dozen times, I came to the conclusion that it was a defect to have such a relay as the fans would run on shut down till the motor cooled to a safe level. This also benefited the turbo greatly. All Saabs were equipped with the time limit relay with the exception of Trionic and new generation 900. The function of this relay was to limit the amount of time that the radiator fan would run after you shut the motor off to 15 -20 minutes. Under the hottest days in central US, the fan will run no longer than 10 minutes. If you still have this relay ....you should deal with it because its a time bomb ticking away.

On the Antifreeze issue. The New Generation of antifreeze called long life stuff, is Propylene Glycol (PG) and the antifreeze as we have known it, is Ethylene Glycol (EG). (EG) is Poison and I pray that the (PG) will soon take its place. God knows what's in our water supply. I know I have drained enough into the street to kill half the country. A doctor educated me on the effects of (EG) and how bad just a trace was to the body. I immediately ordered a collection vassal from Safety Kleen for around $400.00 and pay 46 cents a gallon to have the old stuff hauled off.

The effects and how well (PG) based coolant performs is unknown to me at this time.

On a recommendation level, I have used Mercedes Antifreeze with great success. A example would be a 96 9000 Aero I had in for a head gasket in the spring of 2002. This Aero had 85K on it and I had the Mercedes Antifreeze in it sense 55K. Prior to that It had the Saab Blue antifreeze in it. When I went to remove the head ...I took the head bolts out with a 3/8 ratchet when normally it takes a 3 foot breaker bar to loosen them. On examination, there was no corrosion or erosion at all on the block or head surface. Another indicator of the corrosion issue is when replacing the thermostat. Note the condition of the sealing surfaces after you scrape the white powder away. You are left with pitting in the metal from a corrosion invasion. You can bet the coolant passages in the head around the head gasket have been attacked too.

Conclusion:

I service as many or more of these cars that have not had head gasket failures either due to previous replacement elsewhere or early replacement with the Mercedes Antifreeze or the Saab Blue stuff or good quality antifreeze and service before I met them. As time passes and the miles accumulate, I will have a better understanding in the future.

In the last year as the 9-5 and 9-3 models have become of age "3 years or 30K" and in the coarse of major service, I find that the Saab Blue antifreeze is equal to the Mercedes antifreeze in effect of corrosion retention and metal discoloration. My recommendation is to use only this antifreeze and to change the thermostat to 82C from 89C in a effort to make it to 300 - 400,000 miles without having to pull the head.

The Block Repair Procedure:

Special prep is required to protect the other parts of the motor and conditioning of the metal in the damaged area. I start by removing the block drain plug so the residual coolant in the block drops to a minimum level. Take a hard pointed device and scrape out all the flaking rust from the damaged area. use a small dremel type grinder or a gasket removing pad and tool works well. Brass wont stick to rust so get as much as possible. Take all precautions to mask off any engine orifice in the area and special precaution to the cylinder bore. I treat this area with special attention. I lay a bead of grease around the piston circumference than a shop blue paper towel and another bead of grease around the cylinder bore and another layer of towel. This way, anything that gets through will be captured. After the deck of the block is cleaned and conditioned Drop #1 piston to the bottom of the bore and fill half full with water. Soak 4 red type shop towels in water and stuff one into #1 bore and the other 3 over and around the timing chain rails as a heat shield. Make sure the water level in cylinder #1 is about 1/2 inch above the shop towel at the lower end. Important .... I use the sound of the water as it boils, as a indicator of desired temperature and when to start the brass flow and when the heat is too much for the area. Remember the timing chain rails nearby are plastic. Keep them wet and they should be no danger as you are far enough away to direct the heat away from these items. Use a high heat setting at the torch tip. The center part of the flame should have a tail about 1/3 as long as the whole flame. Use it to preheat the block in that area, keeping the flame moving back and forth along the damaged area and beyond. The idea here is to preheat the block as cast iron dissipates heat quickly. Listen to the water in the cylinder. When the boil becomes rapid, up the o2 level so the feather in the center of the flame is in neutral condition. Now take and concentrate the heat just before the damaged area, with the tip of the torch moved close to the surface and straight at the target. Start dabbing the self fluxed brass rod into the concentrated heat area till it forms a puddle. Start the flame moving in a small circular motion to mix the melted puddle and angle the direction of the flame that you want the brass to follow. The brass will chase the heat. You control the size of the brass bead by the temperature, angle and speed of the torch. Brass don't mix and fuse with the iron as in the case of welding that requires high heat. Brass adheres by capillary action and cast iron has lots of those. Brass lends itself well to this application. After you lay a bead across the damaged area, the water in the cylinder will start sounding like its water boiling in a frying pan instead of a pot ...Time to back off with the heat. Wet the timing chain rails again with water on the wet shop towels that shielded them. Allow the block and worked area to cool down on its own.

The next step is to clean out the cylinder. A shop vacuum works good with the proper end attachment. Prepare the area for the onslaught of free radicals that will be liberated with the grinding and filing.

Again its wise to stuff the cylinders with paper towels and grease in sandwich formation. Tape off every opening you can. On the small hole that supplies oil to the head, I twist a wick out of a piece of blue shop paper towel and use tweezers to push it into the orifice enough that the file will pass over it and I can pluck it out when done. Also on the final cleanup apply suction to this orifice to make sure all contamination is out.

I use a small grinder to knock off the high spots of the brass bead and hand work the file across the block surface, using the surface as a guide. The file will remove the softer brass and slide across the metal of the block if you apply the correct force. Draw the file in various directions to ensure flatness till the metal of the block appears around the outside of the filled area. I use the sharp edge of a razor blade as a level and indicator. You can use a flash light on the back side of the blade and gauge low or high spots. I use this technique on determining low spots as the light will shine through. After you are sure the worked area is flat and true, clean up the area. A high suction vac or syphon gun works well here. Get at every nook and cranny to ensure no contamination is left behind. Continue on with the head gasket install.