help !

[mojobaby]

Melissa, if that's your new idle mixture screw on the right in the above photo, then I think it's point is also damaged, it should be a lot sharper and longer.

Here is a photo of mine


Here's a photo that MarioZg took of his broken one next to a new one

 

[Melissa]

Melissa, if that's your new idle mixture screw on the right in the above photo, then I think it's point is also damaged, it should be a lot sharper and longer.

Here is a photo of mine
View attachment 24058

Here's a photo that MarioZg took of his broken one next to a new one
View attachment 24057

it does look smaller than that, you're right. what carb is that from ? mine is a V05 074A no vacuum adv. I also have a V05 074B which has a vacuum adv, think it's for a gtl, not sure tho.

 

[mojobaby]

Just to confuse you even further.....
My GTL has V05 078A which has a vacuum advance unit connected to it
My 845TL has V05 075B without the vacuum advance.

The mixture screws are not compatible. I once tried to swop them around for my MOT but it didn't fit.

 

[Melissa]

Just to confuse you even further.....
My GTL has V05 078A which has a vacuum advance unit connected to it
My 845TL has V05 075B without the vacuum advance.

The mixture screws are not compatible. I once tried to swop them around for my MOT but it didn't fit.

they made so many different ones! I've got 2 old carbs I got for 10 euros they both have the slightly smaller pointy version..both V0574A

 

[Melissa]

I think both angel and myself have had the most experience over the longest time on Renault fours and we both have respect for each other and most of the time agree but unlike Facebook where you can tag another member I was grateful when he also agreed with me on the spring sadly I now have to do a lot of more modern Renaults and some of my knowledge on Renault 4 was is from a long time ago but given a choice I know what I'd rather be working on hopefully you'll get this sorted soon

Hi Paul, I've continued working on engine, then removed plug on cylinder 4 spark plug, engine does not cut out (does with all others)& then put a bit of oil in no 4..massive difference, idle completely smooth on 850rpm..took her for a run & it's better then starts to get worse..suggests worn/broken piston rings? thanks for any advice

 

[AdamWilkes]

Sounds like a result! Time to get the head off & have a look.

Just a note though: the combined exhaust/inlet cast-iron manifold can turn weird shapes over time - mine needed milling flat after flanges were found at different levels & not sealing even with new gasket. Just a thought for the future!

 

[Melissa]

Sounds like a result! Time to get the head off & have a look.

Just a note though: the combined exhaust/inlet cast-iron manifold can turn weird shapes over time - mine needed milling flat after flanges were found at different levels & not sealing even with new gasket. Just a thought for the future!

yep finally feel like I'm getting somewhere.cheers for advice

 

[AdamWilkes]

Is there any special potion that can be poured down the bore to free up any stuck rings? If they stick in the grooves, they will fail to expand to take up the gap as they wear, so the wear that does happen makes a lot more difference to the compression. Just possibly that would happen and be an easier fix!

 

[André4Renaults]

I've heard it said that soaking the bore in diesel fuel for 24 hours can do it, but I (think!) I heard this back in the 1970s when working in a VW dealership.... my memory might be playing tricks, but it could be worth a try.

 

[mr-reno-139]

Hi Paul, I've continued working on engine, then removed plug on cylinder 4 spark plug, engine does not cut out (does with all others)& then put a bit of oil in no 4..massive difference, idle completely smooth on 850rpm..took her for a run & it's better then starts to get worse..suggests worn/broken piston rings? thanks for any advice

I I presumed and that you had a compression test fairly early on and your symptoms didn't sound like a misfire more like a surge maybe a video of it running would have have given me more of a clue if you're now down on compression due to piston ring problems pretty sure you'll end up either replacing the engine or getting really involved fitting pistons and liners doubt that changing the Rings themselves will have any worthwhile results

 

[Melissa]

I've heard it said that soaking the bore in diesel fuel for 24 hours can do it, but I (think!) I heard this back in the 1970s when working in a VW dealership.... my memory might be playing tricks, but it could be worth a try.

yes I read that in John Muir's book How to keep yr VW alive, pour a quart of diesel down the carb on v old tired engines!

 

[Melissa]

I I presumed and that you had a compression test fairly early on and your symptoms didn't sound like a misfire more like a surge maybe a video of it running would have have given me more of a clue if you're now down on compression due to piston ring problems pretty sure you'll end up either replacing the engine or getting really involved fitting pistons and liners doubt that changing the Rings themselves will have any worthwhile results

No, I started with the carb as the previous owner told me he had issues with it, once I found the end of the mix needle broken off I presumed a new carb would sort it...then carried on my searching, this has only happened since not being driven much over winter.

 

[mojobaby]

Like Mr Reno suggests, before you take a more drastic step, get a compression test done. That will definitely tell you if you have a problem with your rings, or the valves on that particular cylinder.

Edit: For some unfounded reason, my money is still on the carb as being your problem

 

[Melissa]

I wish it was the carb..I've never done a compression test before & my assistant just flew home! Hopefully get it done tomorrow so I can plot my next course of action!

 

[Melissa]

I I presumed and that you had a compression test fairly early on and your symptoms didn't sound like a misfire more like a surge maybe a video of it running would have have given me more of a clue if you're now down on compression due to piston ring problems pretty sure you'll end up either replacing the engine or getting really involved fitting pistons and liners doubt that changing the Rings themselves will have any worthwhile results

Compression test done & pretty much equal from all 4, all about 150 PSI..which ain't too bad for an old gal (the car not me!)..so does that seem to indicate sticky valves? if so what can be done? cheers all.

 

[mojobaby]

Well thats a relief! But it still doesn't solve your problem.
I'm sure that your valves are fine. Do you have the surging only at idle or when you're driving as well, (which must feel quite odd)?

As I mentioned before, I'm sure it has to do with either fuel supply or air supply being irregular. Either a blockage somewhere or an oversupply.
Have you checked the filter in your fuel pump?

 

[Melissa]

Well thats a relief! But it still doesn't solve your problem.
I'm sure that your valves are fine. Do you have the surging only at idle or when you're driving as well, (which must feel quite odd)?

As I mentioned before, I'm sure it has to do with either fuel supply or air supply being irregular. Either a blockage somewhere or an oversupply.
Have you checked the filter in your fuel pump?

I think I'm going to take the head off, even if it's sticky valves it's an indicator of a problem that needs to be sorted inside. The previous owner didn't do reg oil changes so I think it's time she had a proper clean out, I'm sure she's totally filthy inside, well that's the weekend sorted!

 

[mojobaby]

Just a reminder, which I'm sure you're aware of, once you've loosened the head bolts, make sure you don't turn the engine over as the paper seals under the cylinders/sleeves will be dislodged.
Yes, I agree, I'm sure you'll get a shock when you see the inside.

 

[Melissa]

Just a reminder, which I'm sure you're aware of, once you've loosened the head bolts, make sure you don't turn the engine over as the paper seals under the cylinders/sleeves will be dislodged.
Yes, I agree, I'm sure you'll get a shock when you see the inside.

It's been a while since I did one, I was just reading your posts when you stripped your engine down, very helpful thanks.