2.5na Rough Starting From Cold

Greetings,

My 2.5na is a great engine, but when starting it up from cold, it sounds rough as hell. It actually sounds like it's galloping for 5-6 seconds before it sorts itself out. If I give it some revs then it obviously sorts itself out quicker.

I swapped the glow plugs this weekend and it hasn't really made a lot of difference. How long should I be letting the glow plugs glow for? I've not tried anything over 10 seconds.

I also get the white smoke at startup that some people are likely accustomed to, but that soon clears and it doesn't smoke after that at all apart from a bit of black when I'm struggling to get up a hill..

Any ideas on what I should look for going forward? I'm not sure she'll like winter if she starts up like this in mild weather!

About 15secs for the glowplugs But all N/A & TD landys are a bit ropey when they first start up.

I give mine 30 seconds followed by about 10 seconds of glowing once it's cranking and it is rough as hell from a cold start when it's cold out! It's just what they're like. It's probably down to the whole pre-combustion chamber system of diesel "injection". Rather than having a nice fine spray of direct fuel that the TDi's have, the N/A's will be spitting and dripping a more than necessary amount of fuel in all sorts of wonderful patterns into the cylinders until it gets its arse into gear and starts to warm up a little, hence the clatters, the wobbles and the bangs! The CAV pumps are designed to over fuel on startup providing the cold start mechanism is in good order and working properly (the cause of excessive white smoke).

-Pos

I had the same problem when I first bought my td. 30 secs glow then 10 secs cranking it then splutterd to life but sounded like it was about to drop the crank through the bottom of the engine. White smoke filled the street for about 2 miles. A few weeks later my timing belt snapped so I got a new one fitted. When it was done, my mechanic said that the timing was well out. After that was sorted my td starts first turn with 10 secs of heat and a small puff of smoke (no I'm not lying! 19j) so it might be worth checking your timing.

Cheers for the replies! It sounds like mine isn't nearly as bad as you guys I'll see how she is on 15 seconds of glowing tomorrow.

Pos: Are you saying you kept glowing the plugs after the engine has started? I just give mine some revs, seems easier!

D.G.F.S - Injection pump timing? I haven't really touched on that before. The timing belt itself only has a thousand miles on it or so, so I'd imagine that's ok I might get the pump timing looked at though.

Thanks again. Tom.

It fires up after 15 seconds of glowing no problem but I give it 30 as a matter of ensuring it will start on the coldest of mornings. The glow plugs in your N/A regardless of which brand they are will take at least 6 seconds of constant current to glow anyway - take them out and test them! I do give it a further 15 or 20 seconds of glowing once its cranking too just to help vaporise the fuel. They do have a very good cold-start mechanism in the fuel injection pump which will only kick in providing you do NOT press the clutch and you do NOT press the accelerator on startup. Once its cranking you can deck it all you like!

-Pos

I wasn't meaning that your timing belt was on it's way out, it's because when mine snapped and the timing was set correctly when the engine was assembled it ran better than ever. Does yours run rough once warmed up, use more fuel or seem sluggish on acceleration? If so, take a look at the spray pattern of your injectors, if one or more are spraying incorrectly that will cause problems.

after she's got past the galloping/chugging stage (5-6 seconds after she fires up), then there's no rough running at all. She's absolutely fine. W/ regards to seeming sluggish on acceleration, then... well... what can i say...it's the 2.5na! I think she's alright though, and last time I checked on a tank, she'd done 26.8 mpg which I think's pretty good

gf has the landy today, so I still haven't tested her with some more glowing action

Well as what Red and Pos said, give her a bit more glow than normal. Otherwise, it sounds like u have got a gud engine.

Key to starting this engine is heat the glows for a glow period that suits your engine (you can also check manufacturers specification as they all take a different length of time before they reach peak temperature) and then turn the key. As soon as it starts give the throttle a blimp to give all cylinders a blast and get the speed up, then hold it on the throttle enough so that it doesn't seem too rough. If you let the engine idle away roughly they will knock lumps out of the crankshaft and crank bearings.

I had bosch glow plugs fitted to my 2.5NA and 7 seconds was about the longest I ever needed to give them (it said peak temp in 7 seconds), any longer made no difference, in the summer it was about 4 - it was still rough as hell though on a cold morning, white smoke of the unburnt fuel and things... ran like a dream after a warm up.

I gave it a long 15 seconds yesterday, and hey presto, she started up without the horrendous chugging and spluttering. It looks like she's a good old girl after all

tombardier said:

I gave it a long 15 seconds yesterday, and hey presto, she started up without the horrendous chugging and spluttering. It looks like she's a good old girl after all

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I've just picked up a 200tdi can't wait to get it up and running. It'll be interesting to see what a difference it makes

-Pos