Since it's in the shop being prepped, I was thinking of having the tech seafoam the engine since it's already over 120K and has burned 87 Octane which usually never includes the special cleaners and additives found in higher grades.

I want to make sure there are no "Oh god no! It'll hurt Volvo's special Hassenfeffor Confabulator" type surprises.

http://forums.swedespeed.com/showthread.php?158235-xc90-3.2-washing-engine-bay#/topics/158235

Basically, if it's a V8 don't do it or find another method to cleaning under the hood. If it doesn't have the counterbalance shaft (and issue) then you're most likely in the clear.

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Edit: Apologies, I jumped on the phone to respond, thinking you were asking if you could wash the engine bay.

 

http://forums.swedespeed.com/showthread.php?158235-xc90-3.2-washing-engine-bay#/topics/158235

Basically, if it's a V8 don't do it or find another method to cleaning under the hood. If it doesn't have the counterbalance shaft (and issue) then you're most likely in the clear.

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I think he's talking about injecting Seafoam into the engine.

 

Seafoam isn't a degreaser or surface cleaning product. It is an internal engine solvent and cleaner that you hook into your intake while the engine is running, and the spray breaks down carbon deposits and gunk on the throttle body, the combustion chambers and whatever is left on valves.

It's an inexpensive engine clean without all the special chemicals and equipment needed for a full on engine flush.

 

Still not following if you got the XC90 yet or not (based on your signature). This car is a 3.2 with a pretty simple PCV, might be overkill to do a Seafoam treatment (oil or intake) but probably not going to break anything per se if you follow directions.

Not a super common thing that folks do (based on the number of posts this subject). Did my '05 (2.5T) with an oil treatment a few months back in an effort to improve the PCV drain paths, not sure if it improved anything but the engine is still running fine. Ran with it for around 300 miles of driving, then changed out with a new filter.

 

Doing this has not been a "thing" in the XC90 forum, but it was ALL THE RAGE in the R forum for years. I haven't seen it mentioned there in quite a while, but when I first got my R, it was a very regular topic.

http://forums.swedespeed.com/showthread.php?120895-How-to-Sea-Foam-your-R
Here and a million more threads. lol

 

Agree, seems to be more of a 5-6 cylinder turbo "thing" than with the other engines.

I'll drop my oil pan before the summer is up to do new sump seals and clean the square passageway to the oil trap, when I do I'll take some photos.

 

I did this on my 850r, and s70 t5. with great results - I pressure tested the cylinders before and after and some went from upper 150's to 170psi - no kidding, it worked great in those cars, cleared out a ton of garbage (had a long trail of white smoke after injecting the stuff).
I also tried it on my 04 xc90 T5 but the results were less impressive.

A couple of things to note: (from my experience and I am by no means an expert)
- You need to red line the engine to burn off the deposits inside - you cant redline while parked or in neutral in the newer drive by wire cars. The result what the XC90 could not burn off as much as the 850 and s70
- The increase is more noticeable on turbo engines where more garbage builds up inside the cylinders due to greater pressures and stuff.

I am curious to see if anyone has done a test on their cylinders in newer cars before and after the seafoam treatment.

If I had to rate the effectiveness of such a treatment I think it would be as follows: from greatest to least:
- older drive by cable turbo cars
- newer drive by wire turbo cars
- lastly - newer drive by wire non turbos (not because its less effective, but because there would be less to burn off unless poor quality gas is used)

Just my 2 cents feel free disagree

 

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I am curious to see if anyone has done a test on their cylinders in newer cars before and after the seafoam treatment.

I would not expect too many responses on this. You are in the rare class of owners who do a leak down / compression test.
Most people don't even know what this is, let alone to do one and then record and compare results before and after.

Ye olde butt dyno is the most prevent method for the majority of folks.

 

This is a topic of discussion that exists on every forum I have ever visited and will never end ...

1. 87 octane gas in the USA does have (special) cleaners and additives ... but it depends on the brand(s) you use. If it is a TOP TIER brand, it will have beneficial detergent additives - https://www.toptiergas.com/faqs/

2. Being a chemist, I researched this once. My favorite brand of gas in this part of the country (in order of affordability) are Shell, BP and Costco (yes, Costco!).

3. You can approximate the additive package that most Top Tiers use by adding a 20 oz bottle of Techron Fuel Additive (not fuel cleaner!) - http://www.techron.com/ and filling your tank with "cheap" gas not on the Top Tier list. Techron is regularly on sale at your favorite auto parts store for about $12 for a 20oz bottle.

Although at $12 a bottle that works out to 60 cents per gallon when filling a 20 gallon tank in a XC90, so you might as well buy Shell 93 Premium gas at full price.

4. Yamaha V8 engines are extremely forgiving when it comes to burning "gasoline". But one thing that no internal combustion engine likes is moisture, or water in the gas.

With 15% ethanol blends, especially in colder regions of the US, it becomes crucially important that you keep fresh fuel in your tank and use an ethanol treatment every so often. Ethanol will pick up moisture from the air in your tank. Sta-Bil and Seafoam are the most popular products for preventing this, by chemically altering the ethanol. But they are only effective if they are used as a preventative measure, not after gum and varnish has formed.

5. If you do believe that you have gum and varnish, use a TOP TIER gas for several tankfuls (just like the ad says) or 10,000 miles, and you will clean your engine, in a controlled and steady fashion, not with a one time flush!

GL

 

When I was sixteen I scored a 58 Ford with a Y block V-8 for $40. I remember running a quart of Rislone engine cleaner through it and the cloud of smoke from that engine rose about fifty feet into the air. It ran really good after that.

I'd be scared to try something like that engine cleaner with the Volvo. I have put Lucas fuel injector cleaner into the tank but haven't noticed much or any difference in the way it runs. Running it on a trip at highway speeds does seem to make it run better though. Maybe if we make it back to Alberta I'll try some premium fuel. So far its always been regular.