Flushing/internally cleaning an engine

**Tracker1** · #1 12-31-2012, 04:02 PM

I admit I have never done this, or seen it done, so I was wondering if it is some sort of urban myth. I have heard of diesel and transmission fluid - and maybe there is some sort of singular cleaner for this purpose? I have a high-mileage '78 T/A that I want to avoid taking apart, but shows grime on the dipstick and under the valve covers and generally makes a mess of its PCV system with oily gunk. So If I want to flush it internally, who has had good results and with what method? As always, thanks in advance for your knowledge.

**Lynn** · #2 12-31-2012, 09:49 PM

I am not aware of anything that is <span style="font-weight: bold">safe</span> short of disassembly. Any foreign substance you introduce will have to be somewhat solvent based. You run the risk of causing damage to seals and gaskets. Just not worth it.

You can get <span style="font-weight: bold">most</span> of it by pulling the valve covers and oil pan. Nasty job.

**napa68** · #3 12-31-2012, 09:54 PM

Des,

I have used Seafoam in the past on a couple of cars. I ran a can for about 15 minutes at a hot idle. I does a nice job but it has it's limitations. Buyer beware...............there are no free lunches.

Tim

**njsteve** · #4 12-31-2012, 09:56 PM

The biggest crud retention device on a Pontiac engine (assuming there's a Pontiac and not an Olds 403 under your hood) is the valley pan. If the valve covers are filled with gunk, then the double-walled valley pan under the intake manifold has around 5 pounds of carmelized/fossilized goo inside it. The only way to get that out of there is by removing the valley pan and hot tanking it. Or replacing it, of course. That gunky PCV you mentioned is a red flag for the valley pan syndrome.

If you have access to a boroscope you can do an exploratory colonoscopy in the PCV oriface. It will probably scare the crap out of you. (no pun intended) [img]<<GRAEMLIN_URL>>/grin.gif[/img]

The last thing you want to do is run some kind of solvent that would partially dissolve that brick sized, iceberg of crud and have it continuosly flood your engine with crap.

Best idea would be to remove the valve covers, intake and valley pan and have them hot tanked. The intake itself can also store a bunch of crud in the internal heat riser crossover.

**Lynn** · #5 12-31-2012, 11:33 PM

"carmelized/fossilized goo" I think I saw that on a menu once.

Sound advice from Steve. I would also remove the oil pan and either clean or replace the pick up. Mr. Gravity still likes taking SOME of that "carmelized/fossilized goo" stuff downhill and much ends up in the pan.

**SmallHurst** · #6 12-31-2012, 11:42 PM

The Olds 403 can also contain that iceburg of crud. We are proud owners of the Turkey Tray intake gaskets. Pulling an intake may seem like a chore, but it beats pulling the engine after you have starved (insert engine part) of oil.

**miket1** · #7 01-01-2013, 02:55 PM

Many years ago, my brother in law, who never changed oil, ever, had a 400 pontiac engine that he got all sludged up, i pulled the drain plug and it was and it was caked over so bad that no oil would run out, finally got it drained,added 4 qts. of 10w30 and 1 1/2 qts. diesel fuel, let it idle only, no driving, for over an hour,drained, ran new oil 1 week than we repeated the process once more,it cleaned out nicely and the new oil stayed clean, no problems.

budnate · #8 01-03-2013, 12:46 AM

my nephew drug home a 90's v-6 mustang like that a couple of summers ago...down at the grease monkey oil changer guy he had a product they ran in the motor at idle for 15 mins, car had like 150k and I dont think the oil was ever changed much....no BS motor cleaned up, oil stayed clean even months later, would not believe it if I hadnt watched the whole deal...charged us 30 bucks for the snake juice.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: miket1</div><div class="ubbcode-body">Many years ago, my brother in law, who never changed oil, ever, had a 400 pontiac engine that he got all sludged up, i pulled the drain plug and it was and it was caked over so bad that no oil would run out, finally got it drained,added 4 qts. of 10w30 and 1 1/2 qts. diesel fuel, let it idle only, no driving, for over an hour,drained, ran new oil 1 week than we repeated the process once more,it cleaned out nicely and the new oil stayed clean, no problems. </div></div>

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