How to de-grease underside of an old car?

D

DaveInLA

New member
I was under my old car changing the oil and kept on noticing all the dried and caked oil that had gathered from past (years old) leaks. I tried wiping some of it off with a rag, but a lot of the stains are stubborn. I want to clean it mostly off not just so it looks better, but so I can determine if and where my car might be leaking from.



I have a can of Gunk spray-on engine cleaner (foam) that rinses off with water, but I'm not sure if that's a good idea. I try to keep water away from my engine, but on the other hand, the underside gets exposed to water during the rain.



The alternative is to simply spray the most offensive parts with brake cleaner and wipe off. Of course, I'd try to cover the rubber and electrical components. Or I can spray the stuff onto a rag and use that to wipe.



I'm not looking for the bottom to be squeaky clean, but it's pretty attrocious right now. What do you think?
 
I'd use Gunk and a PW, as I used to live up North and pressure wash my undercarrage weekly, and I never had any water problems. It's designed to take a puddle at 70MPH, so it'll take almost anything you can throw at it, as long as you're not aiming for deliberate damage. Brake cleaner is pretty nasty stuff, I try to avoid using it whenever possible. The other option would be Gunk and a brass brush, then you could probably avoid using the pressure washer and just use a hose. I don't really see any need for it, but if it makes you more comfortable, go for it.
 
Nothing works better then a hot water steam cleaner while on a hoist. After you have gotten the heavy stuff off spray on some good degreaser and let it soak and steam/pressure clean again.

Once everything is clean you can spray on some high tec anti rusting spray on and if you like a spray on undercoating on top of the high tec anti rusting spray.

If you have a bad oil leak/s is because your seals/gaskets are bad what you can do is use a heavier weight oil so it don’t leak out as much. But every engine is prone to build of cake on oil. Also make sure the PCV valve is working good. PCV valve should be replaced every year.



REMEMBER don’t let waste water go down the storm drain
 
Any of those methods will work fine, as will using a solvent such as PrepSol/AutoInt New Car Prep/etc. (but consider the fumes with stuff like that an brake cleaner).



When I did the undercarriage of the '84 RX-7 I used P21S TAW, EFHI, and Hi-Temp Engine Cleaner, agitating with brushes and also using a steam cleaner. FWIW, this job taught me that I needed a better steam cleaner ;)



When I did the undercarriage of the '75 Jag (talk about a greasy mess!) I did the worst of it with Simple Green and a pressure washer, again scrubbing with brushes.



And yeah, give some thought to the nasty runoff.
 
"How do I dispose of the dirty runoff?"

Good question, you have to jack up your car so you can go underneath and you have to do that on concrete maybe you can get old towels to make a dam to catch the oil in the water? Maybe you can rent a hoist in a shop for an hour that would be the best thing?
 
How do I dispose of the dirty runoff?



I usually just let it run off to somewhere it'll evaporate (grassy area, concrete pad, street) and hope for the best. Never had to deal with wastewater reclamation (where I come from, SOP is letting it run down the storm drain), so some of the cali guys might be better experts on that.
 
One thing for certain...make sure you use safty goggles..the ones that cover the whole eye area....



I was cleaning a area under my son's truck and got some solvent in my eyes...not a pleasent experience...my eyes burnt so bad...I flushed them under the hose for 20 minutes and they still burnt....my son was ready to do a 911...after things got better..I used an eye cup and eye wash...



my vision was slightly blurry for a few days....now I do not spray any type of solvent with out goggles...



AL
 
DaveInLA said:
How do I dispose of the dirty runoff?
Click to expand...



Small kiddie pool from Target or Walmart placed beneath where you are working. Drill a hole just below the lip on one side. Pour wastewater into a jerry-can or the like and dispose of it at your local collection site. Use a biodegradable APC to rinse the pool on your lawn.



Towels will work for smaller jobs but degreasing an undercarraige can get out of control quick! :rolleyes:



themightytimmah said:
I usually just let it run off to somewhere it'll evaporate (grassy area, concrete pad, street) and hope for the best. Never had to deal with wastewater reclamation (where I come from, SOP is letting it run down the storm drain), so some of the cali guys might be better experts on that.
Click to expand...



Hope for the best. . . oil, grease, etc don't evaporate AFAIK. SOP is your local Water Department? What have you observed them allowing to go down the Storm Drain?



When one is specifically rinsing their engine bay or undercarriage of bonded matter, they really should make sure it is deposited in the proper facility for processing. Your local waterways appreciate it.
 
Hope that post didn't come off as harsh, just in info mode. . .



still working on my taxes = lack of diplomacy



:wavey
 
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