[bob3000]

Sounds like a reasonable plan, regarding the replacement of the PCV hoses, try pinching the hoses to see if they still have a good bounce to them. If they stick together when you pinch them they are done, if they have good rebound to them you might be okay.

 

[Summerheat]

Close it up and pretend you've never seen it

 

[leifr]

Close it up and pretend you've never seen it

Ha. I can't do that. 🤷‍♂️

 

[Pequod]

Two of my cars have the Saab Modified Oil Pan created by Bobby Bright.
His family sold the plans to Andrews of Princeton.
Works well, none of my cards ever had the carbon buildup portrayed here.

 

[Dewolf]

Favourite sludge chemical is quality diesel fuel. Mix 500ml to 3 litres of the cheapest mineral oil you can find. Run the engine for 20 minutes. Drain and repeat. Used this method for over 35 years on all sorts of Porsches, Mercs, Volvos etc. Unlike other solvents, diesel will leave an oil film so still maintaining some protection.
The pic attached is a 928 engine that had this treatment pretty much every oil change. The torque specs on the side save me looking it up.

 

[ET160]

I would skip the ATF.

Personally, I wouldn't run any more than 500ml of diesel mixed in the oil.

I do flushes sometimes with kerosene in the oil, but use 500ml or less for about 10 minutes.

It's important to know, though, flushes have their risks.

Rislone and Kreen are other products I've used in such cases.

 

[cleeland]

I'd be concerned that anything you put in would loosen the coked junk where it's adhering, but would not completely dissolve it, leaving giant chunks flowing through the system. I'm not sure what the threshold for "giant" is that would cause problems, but I suspect it's not very giant.

Your original post mentioned a BG product. I've found their tech line to be very helpful in the past. Perhaps talking to them after they've had a chance to view these photos would be helpful?

The other thing you might consider is calling Blackstone Labs--the folks who do lubricant analysis--and see if they can analyze the chunk that's in your hand (or some other chunk) and make suggestions on chemicals that will help dissolve it in situ without harming the engine and other items. Perhaps they can help you form a plan of action with appropriate chemicals.

 

[Summerheat]

I've been down this road before. And I recon that if it is running fine, just let it be. Maybe do 3k mile oil change intervals, and start cutting open your filters to see if it's dislodging anything.

Realistically, you can buy a good condition motor from a scrapyard for about 250$. That motor will be in arguably better shape than the one you pictured. How much time and money are you willing to put into an engine that still wont be as good as one you pulled from a scrapyard?

There isn't a solvent in the world that will dissolve all that carbon. There is only so much particulate matter than an oil can hold in suspension. At best its going to start flaking off in chunks. At which point you'd have a completely different problem.

If your willing to put in the work yourself. The only type of cleaning I'd recommend is to take the timing cover off and scrapping off the carbon outside the car. You'd get a much better clean this way. Also, this way you can prevent any large chunks from getting in places you don't want them.

 

[leifr]

I just got off the tech line with BG. They recommended that I run their Dynamic Engine Cleaner product through the engine. They said it's an oil replacement that's designed to liquify carbon. It's got more detergents in it than BG109 and apparently they designed it for VWs for the series that was having a lot of carbon buildup/sludging issues. The report is that it will not cause chunks to fall and block the pickup screen.

Here's the procedure: Dynamic Engine Cleaner | BG Products, Inc.

Once I run it they said to pull the valve cover and check how it did.

 

[Summerheat]

I'm familiar with that specific system, saw a few videos about it in the past.
Would be interesting to see how it would work for you. Did you get a price for it? Last I heard the service cost 250$ before labor.
BG generally only offers their products through service centers.

 

[Dimadee]

The diesel will do the job. It is an excellent solvent. Given the severity, I would run the first flush with 500ml or maybe a bit more and run the engine at 2000-3000rpm for 20 minutes and then drop the oil. It should be black and stinky. I would then replace the filter and do another cycle with 500ml of diesel again. When the oil starts coming out less black and stinky, I would do another oil and filter change and drive it for 1000km.

I would then tip in another 500ml of diesel and run it for 20 mins before dropping it and doing another oil and filter change.

I am sure you get the idea. Eventually you will run out of sludge

Regards

Tiim

 

[Sticks]

Going back 30 years or so when I was first toying around with old 60s Fords and Holdens/GMs, we used to run diesel oil in them to keep the oil galleries and top end clean.

I was told that the main difference between petrol and diesel oils is the detergent added to diesel oils to combat the higher carbon levels that infiltrated the oil supply. It used to work as tappet noise used to disappear and there were never any wear or overheating issues that I ran into over the journey.

I'm not suggesting that this will fix the problem here... I think the diesel mix flush sounds the best way. I'm just wondering if after the flush, running your engine with a synthetic diesel oil of similar weight might limit future build up.

I'd be interested to know if anyone has any experiences (good or bad) running diesel oil as an alternative... as I'm thinking of going that route myself.

 

[Dimadee]

Hi Sticks,

I think that is a great idea. I have done this in the past as well.

I meant to mention in my last post that I would clean all of the coke off of the rocker cover before replacing it. Most of the junk will be up top as the vapours tend to rise through the crankcase

...Tim

 

[bob3000]

Do you know the cause of the coke/sludge?

 

[Dewolf]

Back in the old air cooled 911 days, Porsche used to recommend Shell Rotella.

 

[leifr]

No, I don’t. I’ve had the car about three years. It had 68,000 miles on it when I bought it. I can guess, but it would be pure speculation. Maybe someone running a low quality mineral oil and left it in there until it burned? Very long intervals between oil changes before upgrading the PCV system to #6?

Do you know the cause of the coke/sludge?

 

[ET160]

I run diesel oil sometimes. You just need to make sure it is also rated for gas engines.

 

[cleeland]

I've run Rotella T6 in the past. Seems a good oil. There was some discussion in the last few years that it had changed formula, but I don't recall the details.

 

[Sticks]

One contributing factor to sludge is premature engine shutdown. Now while our beloved Saabs are "genetically" prone to it, it is also true of any turbo engine from any maker that shutting down a hot engine causes problems with both the turbo and the oil.

Basically sludge is cooked oil. The oil lines to and from and (particularly) the capillaries around the turbo are very hot when the turbo is spinning. So when the oil stops pumping at shutdown, the oil around the turbo can cook. The when the engine is turned on again, fresh oil pushes the carbonised sludge back to the sump.

Now it usually leaves the lines lined with hard carbon thereby reducing the oil cooling of the turbo in future. If hot shutdowns are repeated, this in turn eventually leads to an expensive turbo explosion... or heart attack if you will. This is the reason turbo timers were invented.

A good (scratch that)... essential habit to have with any turbo engine is to let it tick over for a minute or two before turning it off. This keeps the oil pumping around the turbo while the turbo temperature cools down. The bigger the turbo, the longer it takes. In 16 litre trucks engines it can take 3 to 5 minutes. But in cars it literally only takes a minute with a healthy turbo. A Pyrometer is a great tool for watching the magic as it happens. A turbo timer is even better to stop the issue in the first place.

Once again, this is not the single cause of Saab sludge... but it is the same basic principle. So just imagine that the whole engine is (unfortunately) designed with several hot spots throughout the engine and you'll understand what an issue it is.