300tdi Q's-(RPM range, power)

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roverdevin · #1 Post by **roverdevin** » Fri Jun 24, 2011 10:33 am

A question for those of you in the know about 300tdi engines:

This new to me car is feeling a little sluggish, especially before the turbo really starts up. 1st and 2nd gear are a real slog, especially going up a hill. Once I hit about 1800rpm, there's sufficient power, and I can cruise fairly nicely on the highway...but long hills drag me right back down, (4th gear/70kph.) What's the typical power band and rpm range for this engine?

I have checked all the hoses and flushed the intercooler. I am gettiing up to 1.2bar boost at the manifold when really pushing. There's a very small amount of dark smoke at full boost.

I have heard this could be a symptom of a bad lift pump? Any way to test this? I supose I had better change the air filter, but it looked quite good to me. Fuel filter is new. I'd like to rule out as much of the simple stuff as I can before touching the injector pump, injectors or (noooo!) head.

I'll be taking it in to the specialist next time I can get down to Vancouver and leave the car, but I have a bit of time this week end to tinker.

Thanks for any help,

Sincerely,

Devin B

discojonny · #2 Post by **discojonny** » Fri Jun 24, 2011 11:04 am

I found I really had to dial in my injector pump to get the most out of my 300. There are some good websites out there that explain it in detail. Mine is the same way in that there is not great power until the turbo kicks in(1700 RPM). Mine was dangerously slow until I adjusted the fuel screw.

HeadDamage · #3 Post by **HeadDamage** » Fri Jun 24, 2011 12:06 pm

Yes you have to have the rpm up around 1800 to have power, otherwise it is just an expensive 2.5NA diesel ;) The trick is to row the gearbox to keep the rpm in the right band to keep you on boost. Gear down before you loose boost when climbing hills.

roverdevin · #4 Post by **roverdevin** » Fri Jun 24, 2011 12:12 pm

DiscoJohnny,

Thanks for the reply. I will look into changing the fuelling, but I want to make sure all the other systems are running tip top first.

I suspect a previous owner has already upped boost...I'm getting spikes of 1.2 -1.25bar max, higher than the stock 1.1bar max boost. I wonder if the fuelling has also been upped? I'm getting typical exhaut gast temps of 185C at idle, 350-500C driving, and 550-650C running hard.

This car has also blown a couple head gaskets and has been skimmed...I wonder if the aluminium has gone soft and needs replacing. I'd like to rule out any head gasket problems. I have no signs of it yet, but I want to get the compression checked and coolant tested all the same for peace of mind.

One thing I noticed that I didn't like...yesterday I took it on its first real logging road drive. Coming down I was surprised at how little compression braking there was...I was actually speeding up going down a steepish hill in 3rd low...I hit the brakes at 4000rpm. Does this tell me anything? I have little to compare it with except my Series car. Bad compression? Blown gasket? Maybe I'm paranoid.

discojonny · #5 Post by **discojonny** » Fri Jun 24, 2011 1:08 pm

the engine braking does sound a little suspest, I would guess compression is low, but hard to tell. The boost is High and I have not touched mine as I don't want any problems to crop up. Are you checking boost at the manifold? Your exhaust temps seem quite low so I wonder if it is getting enough fuel. Does it blow white when engine braking when cold? how about black on acceleration? and how loud does it clack at idle? Have you looked at your timing marks? What is this engine in? Lots of questions but I have been over all this with my Disco many times.

roverdevin · #6 Post by **roverdevin** » Fri Jun 24, 2011 2:05 pm

The engine & drive train were bought spanking new as a kit about 63,000km ago, and installed into a NAS Discovery I. Its fairly low km, but has had the head gasket changed a couple times. I would think the bottom end is good, but I've been slightly suspicious of the top end, with its history of gasket problems.

I get no white or blue smoke at any time. A puff of black at startup, and a very slight haze of black when running hard at full boost...SOMETIMES.

My boost sensor is in the plug at the back of the intake manifold. EGT sensor is in the EGR blanking plate pre-turbo. I have not looked at timing at all. Most of the time the boost is between .2 and .6, with spikes up to 1.2

It's my first diesel so I have little to reference to, but my friend said it sounds like his dad's Powerstroke diesel. He was surprised at the diesel noise for so small a car.

I will be bringing it in for a full checkup next week, but I'm just looking for reasons to tinker this weekend. Is there any way to check the proper operation of the lift pump?

discojonny · #7 Post by **discojonny** » Fri Jun 24, 2011 2:18 pm

try the priming lever on the pump. it should give you some resistance when you pump it. You may have to rotate your engine as it may be on the lobe already and not be able to move.

HeadDamage · #8 Post by **HeadDamage** » Fri Jun 24, 2011 4:26 pm

Have you changed and/or cleaned all your fuel filters? My 6.5TD Suburban was a bit sluggish the other day so I changed the fuel filter and it picked the performance right back up to normal.

DaveB · #9 Post by **DaveB** » Sat Jun 25, 2011 9:57 am

Another thing to try...

Have the engine idling and park yourself over the left wing and lean in where you'll be able to listen to the engine closely. Get someone to rev the engine to about 2500 rpm for a few seconds, then turn the engine off from that speed. (definitely not the recommended method of turning off the engine, but for this test, just do it!) Listen carefully to the turbo charger. You should hear a whisper of the turbo spinning down for about 20 seconds or more. If you only hear the turbo spinning down for around 5 seconds, its quite possible that the bearings are beginning to go in the turbo.

Worn bearings result in resistance and slower response of the turbo, and as the bearings wear further the turbo fins will eventually rub the housing and destroy itself (in other words, if you're sensing that its worn, you can get it repaired for MUCH cheaper by dealing with it now).

These bearings are quite prone to wear as most folks used to north american gas engines don't allow the turbo to cool down properly before turning the engine off. Thus the oil coming through the turbo to lube said bearings can get so hot it burns/boils away when its turned off hot. I always let the EGT temp cool down to under 200 C before switching the engine off to avoid bearing wear and oil degradation.

One of our Rover friends that works for a lower mainland school bus shop requires the drivers to leave their busses idling while they sweep out their busses each afternoon – for exactly the same reason. This couple of cooldown minutes lengthens the life of the turbo chargers and the motor oil.

If you have a turbo that's showing signs of worn bearings, it can be rebuilt for about $400. A full rebuild can cost you twice that much if you let the bearings go until the turbo fan rubs the housing.

cheers, Dave

red90 · #10 Post by **red90** » Sun Jun 26, 2011 7:53 pm

All sounds normal to me. The power level you talk about is correct. It is only 110 hp..... You cannot expect miracles. Is there a reason you think this little engine would be faster?

These have quite a bit of turbo lag. Upping the off boost fueling so that it is smokey before boost helps, but the lag will still be there. If you need power, make sure you are in a gear that keeps it above 2000 rpm. The only real fix is to change to a VNT turbo, which will drop this down to 1500 rpm or so.

On engine braking, are you expecting more that the gas engine you took out? That will not be the case.

roverdevin · #11 Post by **roverdevin** » Mon Jun 27, 2011 10:00 am

I'm climbing the learning curve of diesel engines, which is good! I didn't realise that a diesel will compression brake less than an equivalent gas, but it makes sense now after a little research.

I have a feeling my turbo is working ok, as I can feel the increase in power right at 1800rpm, and all through the rev range beyond. It actually pulls quite well up there, other than the long hills. I am thinking I am just a little shy letting the revs climb that high. In terms of where to keep the rpms-- between 2000-4000 is where I should be driving? Where's a safe max rpm?

I did install the digital EGT gauge when I first got it, and wait for the temps to fall below 200 before shut down. I might give the turbo bearing test a try.

What gets me is how bad it is before 1800rpm...JUST enough to move, and if there's an steep hill, I sometimes need to start in low range to avoid slipping the clutch. It could be gearing--It has a 1:1.122 transfercase. With slightly oversized tires, perhaps the 1:1.4 ratio would make more sense?

davran · #12 Post by **davran** » Mon Jun 27, 2011 2:45 pm

Devin,

I have never driven a 300tdi, but my '00 VW Golf 1.9tdi pulls like gangbusters up hills; it's one of the magical aspects of a turbo diesel. Maybe see if you can drive someone else's and compare?

DaveB · #13 Post by **DaveB** » Wed Jul 06, 2011 8:09 am

Devin, another thought...

What kind of exhaust does it have? The exhaust needs for a gas truck vs. a diesel are a bit different, and if he just hooked up the exhaust system from the gas engine that might be part of the problem.

A diesel wants as free-flowing a system as possible, otherwise the turbo will meet resistance it has to overcome before its able to provide more power. Basically a free flowing exhaust allows the turbo to spool up sooner, thus giving you more power at lower revs.

You could test by disconnecting the exhaust at the flange and taking it for a drive. It won't be as loud as you think as the turbo itself cuts much of the noise.

Dave

discojonny · #14 Post by **discojonny** » Wed Jul 06, 2011 8:12 am

I am in north van with a 95 disco diesel conversion. If you are down this way we can meet up and try swapping trucks for a test drive.

red90 · #15 Post by **red90** » Wed Jul 06, 2011 2:40 pm

Dave wrote:A diesel wants as free-flowing a system as possible, otherwise the turbo will meet resistance it has to overcome before its able to provide more power. Basically a free flowing exhaust allows the turbo to spool up sooner, thus giving you more power at lower revs.

Actually, I think it matters less. There have been a lot of dyno testing with exhausts on TDIClub and it never made a difference. On my 200TDI, I first ran with the original 2.5 NA exhaust and did testing with the muffler removed. Zero measurable difference.

DaveB · #16 Post by **DaveB** » Thu Jul 07, 2011 7:47 am

red90 wrote: Actually, I think it matters less. There have been a lot of dyno testing with exhausts on TDIClub and it never made a difference. On my 200TDI, I first ran with the original 2.5 NA exhaust and did testing with the muffler removed. Zero measurable difference.

But, we don't know what Devin's exhaust is currently. An original V8 gas muffler and resonator that could be well plugged by now, or rusted, or it might have something custom built but restrictive.

While the TDIClub may not have conclusive evidence of savings, free flowing exhaust is one of the most popular mods offered by many diesel performance companies, to replace restrictive stock systems.

Comparing one good diesel exhaust to another, or one with no muffler at all may indeed not make any difference, but I'm suggesting that perhaps Devin has a problem with the current exhaust that's restricting flow.

rezdiver · #17 Post by **rezdiver** » Thu Jul 07, 2011 9:20 am

from what i have come to understand the reason for larger exhaust on a diesel is to allow better flow for the hot gasses to escape lowering exhaust gas temperatures. so in a way it does help in performance by lowering temperatures and having the engine and turbo run cooler.

red90 · #18 Post by **red90** » Fri Jul 08, 2011 5:49 am

Dave wrote:....free flowing exhaust is one of the most popular mods offered by many diesel performance companies, to replace restrictive stock systems.

Yes, because it makes money..... Not necessarily because it does anything. Please feel free to show dyno differences where removing a stock diesel exhaust and replacing with something else made a difference. Until you see well developed scientifically sound and unbiased data you should take any claim with a large grain of salt.

Sure, he might have a problem, but his description sounds exactly like a stock TDI. I personally doubt anything is wrong at all.

red90 · #19 Post by **red90** » Fri Jul 08, 2011 5:56 am

rezdiver wrote:from what i have come to understand the reason for larger exhaust on a diesel is to allow better flow for the hot gasses to escape lowering exhaust gas temperatures. so in a way it does help in performance by lowering temperatures and having the engine and turbo run cooler.

In my case (2.5 NA exhaust, then testing with no muffler and now a 300TDI exhaust) there was no change in EGTs. No change in power. No change in turbo performance, as best as I could measure. On a 200TDI with the boost and fueling turned up.

roverdevin · #20 Post by **roverdevin** » Fri Jul 08, 2011 5:02 pm

Dave; all,

The exhaust, as far as I know, is the correct 300tdi Discovery exhaust, which came with the conversion kit.

I have sorted a lot of the issues out, the main ones being very very dirty fuel system, and poorly adjusted tappets. I cruised to Princeton and back this week, and averaged 90kph on the flats (100 wasn't hard to do either) and about 80 up the long climbs. Very acceptable, and a big improvement over earlier.

EGTs were running about 450C cruising and 600C climbing up the passes...I've heard 700C is getting close to too hot?

I still find it a little slow off the mark, but I guess the trick is to keep the revs above 2000 as was mentioned earlier. That's the nature of the beast! I have a feeling my gears are wrong for the tires, and it shows in the shift from first to second.

Interesting findings on the running temp too, and will post that in the thread I started about that.

Thanks everyone for your input and ideas! I'm learning lots.

Dave_F · #21 Post by **Dave_F** » Sun Jul 10, 2011 9:44 pm

Hi Devin,

I think you need to drive another TDi.

This will give you a point of comparison. I also have a 300' and the next time you're in N.Van give me a holler and you can drive my 110. It has a new Top end, head, injectors, etc. It's not perfect but, I think runs well. Don over at Rtech Knows this truck. It is RHD.

I almost made it to Hut, but didn' pick up the message till this a.m...too late then.

Dave_F

The Rover-Landers of BC

The Rover-Landers of BC

300tdi Q's-(RPM range, power)

300tdi Q's-(RPM range, power)