Jet Washing the underside
Jet Washing the underside
Author
Discussion

stubbsy996

Original Poster:

785 posts

242 months

Thursday 31st March 2011
quotequote all
Been offered the use of a jet washer so considering giving the underside a blast. Is there really any benefit in doing this and/or is there a risk of damaging anything?

rog007

5,828 posts

253 months

Thursday 31st March 2011
quotequote all
If it's full of field or salt from the winter, then a spring clean underneath should help. I'd just be careful with the 'jet' bit; maybe more of a wash as you don't want to dislodge or wreck anything. I'm looking at getting mine done, but will probably look for a steam clean then a bit of waxoyl.

Rockster

1,515 posts

189 months

Thursday 31st March 2011
quotequote all
rog007 said:
If it's full of field or salt from the winter, then a spring clean underneath should help. I'd just be careful with the 'jet' bit; maybe more of a wash as you don't want to dislodge or wreck anything. I'm looking at getting mine done, but will probably look for a steam clean then a bit of waxoyl.
I'd not steam clean the underside of the car. This could damage the very nice protective coating (some epoxy based paint IIRC) that does a superb job of protecting the underside of the car from chipping.

Also, the protective plastic panels could be damaged or warped out of shape from the heat.

I treat the undersides of my Porsches to a good rinsing now and then and use a garden hose with a good flow of water but not much pressure. A good dousing is all that is needed to rinse/remove any dirt and salts and such.

Sincerely,

Rockster.

rog007

5,828 posts

253 months

Friday 1st April 2011
quotequote all
Got that Rockster, thanks. You're right about removing stuff, but my steamer is domestic and quite gentle and really will only just remove crud rather than any base stuff; but I will be extra careful.

NBTBRV8

2,066 posts

237 months

Friday 1st April 2011
quotequote all
I found that without you use a degreaser the pressure washer won't move much.

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Pugley

687 posts

221 months

Friday 1st April 2011
quotequote all
I have to join in on this slightly anal thread and confess I have been pressure washing the underside of my cars for years.yikes

I have an angled attachment that slides along the ground under the car and directs the jet at 90 degrees to the bottom. In my experience cold water does not remove wax but it certainly removes mud and more importantly salt. This has saved several cars notorious for rusting from an early grave.

Even though most porsches are galvanised salt slowly eats away at the zinc, gets into seams and box sections, and starts the rust process.

I may be eccentric and I dont really care if the paint is dirty but I dont like to think that the underside of my car is being eaten by salt - even when the sun is shining.eek

PH5121

2,007 posts

242 months

Friday 1st April 2011
quotequote all
I have one of those angled lance things for my Karcher pressure washer.
The Porsche never goes out in winter, but I use it on the other cars to feep the undersides salt free.

Car dealers use the hot pressure washers on their stock to clean them up prior to sale, I don't think you can hurt much cleaning the crud off with one.

Rockster

1,515 posts

189 months

Saturday 2nd April 2011
quotequote all
PH5121 said:
I have one of those angled lance things for my Karcher pressure washer.
The Porsche never goes out in winter, but I use it on the other cars to feep the undersides salt free.

Car dealers use the hot pressure washers on their stock to clean them up prior to sale, I don't think you can hurt much cleaning the crud off with one.
Hot pressure washers aren't that hot.

I've seen real steam cleaners in action cleaning machinery, equipment, old engines, etc. They'll take everything off. Steam (water vapor over 100C and not just hot water at 50C) with some pressure behind especially is a pretty good cleaner.

Also, I've never seen my cars pick up anything that just plain old water wouldn't remove. We are talking just winter road grime and salt residue, remember, not what the car's underneath would pick up driving across a cow pasture.

Sincerely,

Rockster.

PistonAficionado

7 posts

125 months

Monday 6th March 2017
quotequote all
I just take the car to a local static car wash, the ones where you stay in the car while the brushes clean everything up, one of the modes is cleaning the underside, is just a stream of water under the car, do that once the salt season has finished, issue solved.

Cheib

25,360 posts

204 months

Monday 6th March 2017
quotequote all
PistonAficionado said:
I just take the car to a local static car wash, the ones where you stay in the car while the brushes clean everything up, one of the modes is cleaning the underside, is just a stream of water under the car, do that once the salt season has finished, issue solved.
yikes They're not great for the paintwork though are they!

HighwayStar

4,864 posts

173 months

Monday 6th March 2017
quotequote all
PistonAficionado said:
I just take the car to a local static car wash, the ones where you stay in the car while the brushes clean everything up, one of the modes is cleaning the underside, is just a stream of water under the car, do that once the salt season has finished, issue solved.
My car will never see one those... I'd rather leave it dirty than subject it to one of those.

LordHaveMurci

12,336 posts

198 months

Monday 6th March 2017
quotequote all
Used to drive mine through a local ford occasionally!

V8A*ndy

3,697 posts

220 months

Monday 6th March 2017
quotequote all