Td4 DIY leak back testing

rob_bell · Aug 27, 2019

Hi guys,

This is actually for my MG ZTT CDTi with the same Td4 motor. Difficult start, particularly when hot. LPFP is likely dead (can't hear it, have replacement to fit), HPFP appears to be functioning fine.

I have a hunch that the LPFP replacement probably won't fix the problem, so am planning to check the injector leak off. There are a few kits available on the bay of fleas for under 20 quid - anyone have experience with them? Also, anyone know what the correct tolerance measure would be for these Bosch injectors?

websun · Aug 27, 2019

Those cheap chinese injector leak tests are good. BUT make sure you have spare nozzles/leak_off_pipe as you need to connect it there and depending on the condition one or more might break and you won't be able to leave with the car.
http://ebay.co.uk/itm/271427558108 is what I bought but I was lucky and won an auction for like a fiver for the brand new original cable. And complete.
Also make sure you block the return line or you will have diesel on your car, bedroom, bathroom and possible even on the roof. These kits come off with some small whiteish plastic caps to do that.
I find this job quite messy 1st time. Second time is alright but still.

rob_bell · Aug 27, 2019

Awesome, thanks - great advice re replacement return connectors!

Good would be <25 ml in 30sec?

websun · Aug 27, 2019

You need them just in case one breaks as it's a 3quid item but if you don't have it... sad.
No idea to be honest how much it should be, I only used mine to determine which one is the bugger, and it was 4 as it filled up much faster than the others.
Then got a recon one and failed in 500 miles. Life's a beach.
Plenty of guides on youtube and all on how much it should be etc. Also there are two tests, without cranking vs running engine. I think the non cranking one only uses the small tubes and is a bit easier.

rob_bell · Aug 27, 2019

Mine were reconditioned a while back and hasn't done massive miles on them - and reckon they've gone again...

I love this car to bits, but honestly, the German bits are the least reliable parts of the car!!!

websun · Aug 27, 2019

I sincerely doubt that. I am not a big fan of the British engineering in cars and houses, I've seen amazing things on both. Just look at the camshafts on a K series vs this M47.
It's just us trying to get cheap on injectors... Usually they are changed especially after 100k miles. They are not a fortune if you do 10k miles per year for example.
We don't really know how they recon the injectors my guess is cheapest parts available.

rob_bell · Aug 27, 2019

Tiz true. My MGFs always start on the button, first go (assuming that the battery is good). neither has failed me. Never had a head gasket failure, and I've done 100s thousands of miles on it.

My ZTT, while the engine is strong, has had loads of problems with the pumps, MAF sensors etc etc. It's been my least reliable car - but it has been a joy to own since I bought it back in 2004. If the injectors have had it, it'll be the second time in under 102k miles.

andyfreelandy · Aug 27, 2019

Recent test on my Td4 at idle produced about 8ml per minute leak back. Now looking at pressurising input to see if they leak when off. Simple pressure gauge and pump. My fault condition is white smoke for a minute after start up. See my thread on it.

rob_bell · Aug 28, 2019

Thanks Andy

Td4 DIY leak back testing

rob_bell

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websun

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rob_bell

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websun

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rob_bell

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websun

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rob_bell

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andyfreelandy

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rob_bell

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