300Tdi exhaust brake - possible

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Originally Posted by 100I

When you say drive it smart do you mean keep the RPM low?

BBS

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more or less....

dont kick the exhaust brake in when the RPMS are high if you dont have some kind of pressure regulation in place to prevent the valves from floating....

dont leave the exhaust brake on while your changing gears.

you could also wire up so that when the exhaust brake is on and the clutch is up the fuel solenoid gets turned off but comes in when the clutch goes down.

or wire it up so that when you push the clutch down the exhaust brake comes off and the fuel turns on....

Ive seen people on older vehicles with the old school exhaust brakes trying to change down and not making the shift because the exhaust brake is still choking the engine.

Don't know how it would go on the TDihowever I do know that exhaust brakes did some nasty things to the engine components upstream of the gate. Things like burned valves and blow-outs on exhaust manifolds, so wouldn't like to think of what it would do with the turbo-charger side of things.

I also know (from personal experience Dodge 575 V8 petrol) that on a vehicle with a vacuum brake booster system for the vehicle you lose the vacuum when using an exhaust brake. This happened a number of times with a full pantec load of 8 tons I had no boost on the footbrake when decending Mount Ousley outside Wollongong. It will be different if the vacuum for the brakes is generated by a vacuum pump.

So be very careful what you do if you don't have a vacuum pump on the brakes, I'd be adding a vacuum acumulator tank to your brake system before adding an exhaust gate.

Hi Diana,

Was that “Dodge 575” as in 575 cu in?? Wow, that's a big b*gg*r.

I take your points but there wouldn't be too many (any?) diesels around any more (apart from the Series LR diesels) that don't have a vacuum pump, either direct engine-driven like the Tdis, or on the back of the alternator like most Jap engines, would there?

Re. burnt valves and blown exhaust gaskets, I'd think that's likely caused by pressures in excess of what the valve gear/gaskets are designed to handle. Hence my questions about, and preference for, a brake unit with built-in pressure relief.

The idea of suddenly stalling the turbo is a cause of concern but as Rick130 says, squillions of truck engines (light, medium and heavy) seem to do it all the time. I'm guessing that a turbo decelerates very rapidly when you lift off the 'loud' pedal anyway - with very little exhaust turbine energy input, the compressor will 'brake' the whole show almost instantly. So by the time you close the exhaust flap, the turbo is not running very fast anyway (well, relative to its full speed, at least).

On the other hand, shutting an exhaust flap while the engine's at full noise/full throttle could well be cause for the entire manifold/turbo assembly to part company with the block!!

Thanks to all for your inputs. Again, can anyone suggest a particular light truck unit that may make a good starting point?

Ian

Ian,I would start at any of the four cylinders,there are alot in the dyna,canter range.I would check out if the transit,transporter,vito vans have them,they would be even better.I would also strongly recommend changing to a high temp race car quality brake fluid,they are illegal but braided brake lines make an amazing difference to pedal feel. Pat

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Originally Posted by PAT303

<snip>
I would also strongly recommend changing to a high temp race car quality brake fluid,they are illegal but braided brake lines make an amazing difference to pedal feel. Pat

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Without having to spend the huge $ on Castrol SRF, buy Castrol Response Super DOT4 (not to be confused with Response DOT4 :rolleyes: )
IIRC it's only about $35/4 litres and exceeds DOT 5.1 for high performance brake fluids, as well as exceeding DOT 3 & 4.
It used to have Porsche and BMW M approval for their ABS sytems on the old TDS.

Dry BP of 280*C
Wet BP of 186*C

As for braided hoses, you can get ADR approved ones for $$, they use crimped ends (as opposed to motorsport and aircraft standard nuts and olives) and have a rubber sheath at the ends for the infamous 'whip' test and sport a tag with an ADR approval #.
Of course there would be people using Earls -3 hose and ends (very high quality hose and ends, used worldwide to the highest levels of Motorsport) and pushing rubber tube over the ends to mimic the ADR ones (and to my thinking the nut/nipple/olive connection is a superior construction) but it wouldn't be legal, would it.......

Actually I think you can buy Goodridge ADR approved hoses for Land Rovers too. (being from the UK) Also excellent stuff.

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Originally Posted by rick130

Without having to spend the huge $ on Castrol SRF, buy Castrol Response Super DOT4 (not to be confused with Response DOT4 :rolleyes: )

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Originally Posted by rick130

IIRC it's only about $35/4 litres and exceeds DOT 5.1 for high performance brake fluids, as well as exceeding DOT 3 & 4.
It used to have Porsche and BMW M approval for their ABS sytems on the old TDS.

Dry BP of 280*C
Wet BP of 186*C

As for braided hoses, you can get ADR approved ones for $$, they use crimped ends (as opposed to motorsport and aircraft standard nuts and olives) and have a rubber sheath at the ends for the infamous 'whip' test and sport a tag with an ADR approval #.
Of course there would be people using Earls -3 hose and ends (very high quality hose and ends, used worldwide to the highest levels of Motorsport) and pushing rubber tube over the ends to mimic the ADR ones (and to my thinking the nut/nipple/olive connection is a superior construction) but it wouldn't be legal, would it.......

Actually I think you can buy Goodridge ADR approved hoses for Land Rovers too. (being from the UK) Also excellent stuff.

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And is that the same as this? Listed as super dot4 on the pack and available at my local Supercheap, Kmart and Repco.

https://www.aulro.com/afvb/

Arrrgh, you can click on the link and look at the spec. sheet yourselves, the table doesn't hold formatting when I cut and paste.

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Originally Posted by PAT303

,they are illegal but braided brake lines make an amazing difference to pedal feel. Pat

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Pat... Braided PTFE lined brake lines are NOT illegal..

Re-useable lines are...

Professionally crimped versions are available in Australia with FULL ADR compliance and are road legal.

But I agree with the rest of your statement...

I also fail to see the point of adding an exhaust brake to any landy...
You say the brakes "would be hot by then" so I assume you have never suffered a brake failure etc....

Of course brakes get hot... Help them by fitting slotted rotors to the tow vehicle (reduces gassing between pad and rotor) fit higher spec pads and the braided lines...

Your driving style is good, firm definitive braking to speed then use gearing... No issue there.... Keep your trailer brakes working at max by maintaining regularly... (as your doing)...

Yes, the brakes will get hot.... Thats their job..... Turn rotation into heat...
Make sure you have vented front rotors..... upgrade if necessary...

Doesnt take them long to come back to normal temp anyhow...

I had harrop brakes on my 'road/track' car....with no heat in the rotors they wouldnt stop that great...

Heat them up and they were amazing - Didnt take long to heat them either, just a nice hard application.

Somewhere in the club I was with is a photo of the red glow from my front rotors through the wheels..... They were still retarding fine...



Oh...

And people, you cant expect a 2.5L air pump to retard as well as a 4.2L air pump... It just isnt possible :)

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Originally Posted by Tombie2

And people, you cant expect a 2.5L air pump to retard as well as a 4.2L air pump... It just isnt possible :)

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now thats just begging to get picked on....

what if the compressions ratios a lot better on the 2.5l?

what about crank throw or the 2.5 having designed retarder when the 4.2 doesnt?...

assuming your talking about the 2 engines I think your talking about....

doesnt your 4.2 have a throttle butterfly that closes stopping the pump from drawing in air to compress...



just stirrin that pot

Hi Tombie2 & others,

Thanks for all the recent feedback. Perhaps my comment that the brakes "would be hot by then" was too simplistic and I didn't explain my concerns in enough detail. Yes, I'm well aware that brakes run hot and only work at all because friction converts mechanical energy into heat.

My concern is, while I've never experienced fade (that I know of) and never want to, that under the conditions described, I'm pushing the brakes close to their limits on a regular basis.

I could upgrade the Disco's front discs and use better quality lines and fluids but this seems to me to be attacking the problem at the wrong place. My thinking is that it's the caravan's drum brakes that are more likely to overheat and fade before the brakes of the tow vehicle. And drum brakes take a lot longer to cool and recover than discs.

[If the 'van brakes did begin to fade, would you know about it until it started pushing the back of the tow vehicle on a steep downhill hairpin? - sorry, I'm getting into pure speculation now.]

I obviously don't have the relative costs as yet but if the costs of an exhaust brake and the costs of upgraded front discs, lines etc. were comparable, it seems to me to be the exhaust brake is tackling the described problem at it's cause while the latter is tackling the symptoms. That is, if the rig has better engine braking then there's no necessity to upgrade the brakes to compensate for possible overheating. Lots of truck manufacturers seem to think it's worthwhile...

Yes, I agree that "you cant expect a 2.5L air pump to retard as well as a 4.2L air pump... It just isnt possible", all things like comp ratio, etc. being equal. But perhaps a 2.5L air pump with a well-executed exhaust brake may get close to or even exceed the retardation of a non-exhaust braked 4.2?

Thanks again to all for your input.

Ian

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Originally Posted by Blknight.aus

.... you could also wire up so that when the exhaust brake is on and the clutch is up the fuel solenoid gets turned off ....

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I would be concerned with that. The I.P. would be operating with no fuel - won't there be problems with (a) lack of lubrication for the plunger and barrel, and (b) air in the system downstream of the plunger?