Pressure required to clean underside of car.

[HSGB]

Has anyone here ever used their air line to blast all the crud from the underside of the vehicle? I have 100 p.s.i. on tap but it doesn't seem to shift a great deal and I was hoping, because of all the horrible nooks-and-crannies, that it would blast all the muck out of these awkward places as they are totally inaccessable with wire brushes, etc.. How much pressure do you think would be needed to blast all this dirt and muck, not the waxoil but the dried mud and caked on crud, from the underside? Loads of people must be doing this to shift the muck, so I just wondered at what pressure they are getting a decent result from.

Cheers.

 

[Pete.]

Most people use a pressure washer.

 

[maroon]

You can get a hose pipe thingwiejig that will turn your compressor into a jet washer. Probably best off with a decreasing gun. Throw something with the air. water, degreasing gunk. Sand...

 

[Trevorleach]

Even a steam cleaner can struggle on the nooks and crannies, so I doubt an air line will be up to the task.

 

[steveo3002]

yeah agree jet washer , pref steam cleaner is what you need to be thinking about

 

[Wozzaaah]

Trust me, loads of people aren’t doing it.

 

[James1979]

Trust me, loads of people aren’t doing it.

To the OP. I have a petrol pressure washer that I’ve got a 90 degree end on for cleaning under my truck as it’s minging after a couple of days.

Once or twice a winter I take it to the bus garage, bung the boys some buiscuits and beer and they put it on the wash ramp and hit it with their steam cleaner for me on night shift.

That’s well worth doing if you can find someone who’ll do it for you. Loads more efficient than buggering about with airlines and domestic pressure washers etc

 

[brightspark]

1500 psi hot water pressure washer with traffic film remover

 

[wristpin]

No local bus garage but any commercial vehicle workshop prepping HGVs for their annual inspection will almost certainly have the necessary equipment . The HGV test stations are very particular!

 

[HSGB]

I don't have access to any of that sort of facilities, so have to improvise best I can. I have always used an airline to remove dust and moisture prior to waxoiling and has served me well. I did power wash it beforehand , but not with hot water, but unless you can see what you are spraying it's all a bit hit and miss and you have always missed loads when you get it over the pit. The airline is excellent on the easier to access stuff but needs more presuure for the harder to get crud. I have just used the airline to blast out my subframe today, as it is double skinned, worked a treat, blew out massive amounts of moisture and muck from inside, I shall inject wax oil in there in a few days. That's the trouble with the pressure washer, if you want to waxoil the bottom, which is what I want to do it can take a long time for the moisture to dry out on the bottom of the car.

 

[Nick67GT]

I don't have access to any of that sort of facilities, so have to improvise best I can. I have always used an airline to remove dust and moisture prior to waxoiling and has served me well. I did power wash it beforehand , but not with hot water, but unless you can see what you are spraying it's all a bit hit and miss and you have always missed loads when you get it over the pit. The airline is excellent on the easier to access stuff but needs more presuure for the harder to get crud. I have just used the airline to blast out my subframe today, as it is double skinned, worked a treat, blew out massive amounts of moisture and muck from inside, I shall inject wax oil in there in a few days. That's the trouble with the pressure washer, if you want to waxoil the bottom, which is what I want to do it can take a long time for the moisture to dry out on the bottom of the car.

Leave a fan heater under it overnight…..

 

[Trevorleach]

I don't have access to any of that sort of facilities, so have to improvise best I can. I have always used an airline to remove dust and moisture prior to waxoiling and has served me well. I did power wash it beforehand , but not with hot water, but unless you can see what you are spraying it's all a bit hit and miss and you have always missed loads when you get it over the pit. The airline is excellent on the easier to access stuff but needs more presuure for the harder to get crud. I have just used the airline to blast out my subframe today, as it is double skinned, worked a treat, blew out massive amounts of moisture and muck from inside, I shall inject wax oil in there in a few days. That's the trouble with the pressure washer, if you want to waxoil the bottom, which is what I want to do it can take a long time for the moisture to dry out on the bottom of the car.

If you are in the UK at this time of the year the double skinned bits inside of the chassis will not dry, then when you blast the chassis wax in there it can seal the water in, there are some liquids designed to get rid of water from cavities.

 

[Ross365]

1500 psi hot water pressure washer with traffic film remover

I think that is what they used to clean 150 years of soot off Morley Town Hall in the 1960's. I preferred it black and ominous. Does that not do damage to old paint and other protective finishes ? Think I'll pass.

 

[brightspark]

I think that is what they used to clean 150 years of soot off Morley Town Hall in the 1960's. I preferred it black and ominous. Does that not do damage to old paint and other protective finishes ? Think I'll pass.

if its loose it wants to come off anyhows

 

[Ross365]

if its loose it wants to come off anyhows

I think there's a difference between loose and loose after been blasted with hot water at 1500psi. A paint company might say you can blast at 500psi (for sake of argument) and they expect their paint to be good, but move up to 1500psi and maybe not.

Remember; the definition of Quality is "adequacy for purpose". Do cars have to be able to withstand 1500psi - don't think so. I'm not sure which of the car-makers might say 1500psi is "in-spec"; maybe none .The Chief Engineer looking after my cars (both over 20 years old) thinks 1500 psi is way too high.

What pressure do you set your bidet at ?

 

[fizzy]

When I used to get my Land Rover really filthy even the best pressure washers wouldn't shift the muck. Then one day I drove across open mountain in long wet grass - the vehicle was spotless underneath

 

[Turbo]

As has been said, a hot pressure washer & detergent is the best way to clean this. There's bound to be somewhere near you that does MOT washes? Even better if they use a pit to get under the car, you just don't get as good an access on ramps.

As for pressure, having been a service engineer for Karcher I agree that 1500 psi is too much for car paintwork. Most of our customers had their washers jetted down to 1300 psi to avoid paint damage.

 

[steveo3002]

If you are in the UK at this time of the year the double skinned bits inside of the chassis will not dry, then when you blast the chassis wax in there it can seal the water in, there are some liquids designed to get rid of water from cavities.

thats why you do it in summer not the start of winter , i do my clean ups as soon as the road salt /rough weather has gone , and apply any treatment after a long hot spell....i was out there doing it that week it was 40 deg so that it had its best chance of being dry and the product flowing

 

[mtt.tr]

Steam clean would be the best,but for what it's worth

I bought this pressure washer few months back, it's brilliant, simple design and rebuild-able
Not mega pressure but higher flow (you cant deny physics) the low key super duper high pressure jobbies just don't put out enough flow.

CPW2030 - Blackline 1.8kw Commercial Quality Pressure Washer from Rally Design

Blackline 1.8kw Commercial Quality Pressure Washer The CPW2030 is fitted with a commercial quality induction motor which features longer lifespan, better power efficiency, lower noise level and better suited for a wider range of applications than most ch…

www.rallydesign.co.uk

 

[8ob]

There are a few fords around here, just hit one of those at speed. Job done