Hot Soaking A 318, Redux.

[Casey3561]

Well, after a little advising and instructions off unofficialbmw.com, I decided to run the 318 through a hot soak. Results?

Wow.

I still have the first printout from the dealership, when I got the starter replaced, and it says "Surges at idle when cold". It surges no more. Rock steady at about 950 rpm. Pickup has improved markedly, letting it zip along quite well.

Here's a link to a thread where it is explained. I used Seafoam, which can be found at Napa or some other places. $5 for the bottle, a few bucks for the oil change, and I am quite happy.

I found that putting the Seafoam in a water bottle, punching a hole in the bottom of the bottle, and threading the vacuum hose in allows me to rev the engine lightly enough to maintain the flow, while also letting me get full fluid in.

[dblmikeusa1]

Hot soak???

[528man]

never heard of it

['89 635 csi]

Hot Soak Rocks!!!

[thekid]

I asked my friend/mechanic about doing this. He said that with the older BMW engines it was needed from time to time to clean out the carbon. For the newer ones, basically E36 on there is no need unless you never drive your car or turn the car on and drive it for 4 minutes and then turn it off and that's it, then you would possibly need it to help clean out the engine. Also keep in mind that if you really don't need it running your pistons dry is harmful to your car. Glad you had a good experiance with it.

I would adivse people to be careful about doing this, especially in our E36 cars that are fairly clean running. If you put your foot down on the gas every once in a while (or daily like me) there won't be anything in your engine that shouldn't be in there (like carbon build up etc). Just my .02 cents, don't let it stop you you also want to try this.

[Casey3561]

My problem is exactly that. My driving is 100% city, with only a rare foray at highway speed. Turning it on for 4 minutes is a little short, but there are many days where it only gets driven for 15 minutes or less.

[NeverLeaned]

I used to do this to my carborated Outboard every summer. I used a mix of carbcleaner and gas (90% cleaner 10% gas) had a friend try to run the boat wideopen until it died, then repeat til I killed the bottle.

I was also a handy trick on my carbed 442.

I never thought of doing anything like this on a fuelie though. I usually dump a bottle of techron in my tank the tankfull before I change plugs.

Regardless of the method you use, expect the carbon to fowl your plugs and be ready to clean or replace them when done.

Another trick you can do is to use a spray bottle with water.... again I would not even think of doing this w/ a fuelie or a high compression engine... and if you've never done this before then DONT EVEN THINK OF TRYING IT WITHOUT SOMEONE WHO HAS DONE IT! Big time damage to your engine if you do it wrong.

[john_18]

yep...we call it a fuel system flush....did it to mine and got out the rough idle.

[ridikuledind]

I may be interested in doing this..i need more info because i dont want to ruin my engine. ghead

[thekid]

Originally posted by ridikuledind@Mar 11 2005, 10:57 PM
I may be interested in doing this..i need more info because i dont want to ruin my engine. ghead

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You will not ruin your engine doing it. However, it does put an unusual strain on the engine. I had not seen the thread that was linked to in the first post of this thread. However, I looked into the Hot soaking procedure because of another thread we had about it... about a month ago I think. Basically you only need to do it with older cars OR with cars that see very little driving, in city conditions ie heavy stop and go traffic, short runs, for instance if you have a 10 minute drive to work and then 10 back and you stop at a place or two on the way back (errands) every day and that's all your car sees.

There are a few things that you can do, that most people would not recommend. When I asked my mechanic about doing this he told me honestly that there was no need. Basically if you never push your car, acceleration wise, ie never floor or almost floor your car then some things can build up. BUT OH WAIT?!?! you might say, isn't flooring your car bad? Well no not really. As long as you are not red lining the car you really aren't doing damage. Accelerating the wear on your engine, yes marginally (keep in mind you want to wait for your car to warm up, out of the blue is ok). This will help keep you engine free from carbon build up, which is bascially what the hot soak procedure is/was used for, according to my understanding of the procedure and it's uses.

So I would adivse you to think about the conditions your car see's before doing this. If you are doing it to fix an idle problem, make sure it isn't anything else. I would only do this procedure as a last result. My reasons for it, I mentioned in passing in my earlier post and alluded to in the first paragraph. Basically what you do is you are having your car running on Fuel Injector cleaner ONLY and once the bottle of fuel injector cleaner goes in, your car sputters and dies. It dies because there is no fuel or combustable liquid going through the fuel injectors or into the cylinders. Both of which is bad. While I flooring the car (note my reasons for flooring or driving fast is not to aviod carbon build up... it is just a side affect) perhaps does more "bad" for my car than Hot soaking it once, I see no need to do both.

Sry for the long post... waiting for Fedora to finish updating...

[NeverLeaned]

If you car is running rough, try buying a bottle of techron with your next fillup. If your not running smooth by the following check the plugs, THEN come in here and ask about a Hot Soak.

[thekid]

Originally posted by NeverLeaned@Mar 12 2005, 11:07 AM
If you car is running rough, try buying a bottle of techron with your next fillup. If your not running smooth by the following check the plugs, THEN come in here and ask about a Hot Soak.

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or any of the other things that could cause rough idle in the E36 unsteady idle faq.

[kyle_baker]

there is another topic about rough idling that may help... http://www.bmw-forums.com/forum/index.php?...c=34310&hl=idle they suggest cleaning out the idle control valve.