4 cylinder issues

F

Fraserp6

Member
Anyone thats followed anything I've posted on this forum probably has an idea that I've had a few issues with my 4cyl, for a while things have been fine, problems have returned.

I was aiming to start the car the other day to take it out to finally fit my vacuum circuit for the air con, however, I could not get the car to start.

Eventually I called the AA to get the car to start, however, despite being jumped and cranked, the car would not start, only catching.

We fiddled with timing and touched the car briefly, yet it would not start.

One, recovery truck journey later and it's out at my parents, in a garage and with a variety of tools. Yesterday evening I began fiddling. I have a spark going to all four plugs and fuel going to both Carbs, futhermore, when I disconnect cylinder 3 and 4, the car stalls and very nearly dies. When I disconnect cylinder 1 and 2, however, there is near enough no impact on the running of the car.

The car is hugely down on power and struggles to pull away on level ground, so I've no doubt there is something wrong, though when I adjust the mixture on the front carb, the revs and idle will variate.

I've had the rocker cover off today, to check for valve clearances, however, I'm just curious as to the clearances required. The Inlet is to be within .22 to.28 mm and the exhaust is to be .33 to .38 mm? Is this correct for my 1972 2000tc? as a quick check through the clearances would suggest everything is massively out.

It's probably worth noting also, I was losing coolant over a few weeks, which had a direct co-relation with the difficult in starting the car, (more coolant lost, car harder to start) I traced this to a tear in the inlet manifold gasket, which had been letting a slow driping of water into the cylinder bore... Is this likely to have caused damage? as I'd have thought once starting the car would have just burned off any condensation.

There are a few things I need to check, however, I felt that the timing and the fuel mixture were pretty spot on, however, I've never though to have had issues with the valve timiing. I'm going out to check this in more detail, however, without taking the head off (which will require a new Head Gasket, which at current I don't have.) I'm a little at a loss on what direction to go on this.

As always, any help is massively appreciated, particulary when the issue is stoping the car running.... and in turn preventing me from finishing my NADA air con.
 
Fraserp6 said:
I'm just curious as to the clearances required. The Inlet is to be within .22 to.28 mm and the exhaust is to be .33 to .38 mm? Is this correct for my 1972 2000tc? as a quick check through the clearances would suggest everything is massively out.
Click to expand...

In English please Metric means nothing. Inlet 8-10 thou, Exhaust 13-15 thou.

If removing plug leads 1 & 2 does nothing either they're on the wrong way around, or the head gasket has blown between those two cylinders, which if the inlet manifold has failed and allowed coolant to be drawn in, is a possibility because that coolant won't compress, so it has to go somewhere, or it's a fault with the front carb. I think I'd do a compression check for a start.
 
Compression Tester, it's on the shopping list, so far I've survived without one, however, would be beneficial just now.
 
harveyp6 said:
Fraserp6 said:
I'm just curious as to the clearances required. The Inlet is to be within .22 to.28 mm and the exhaust is to be .33 to .38 mm? Is this correct for my 1972 2000tc? as a quick check through the clearances would suggest everything is massively out.
Click to expand...

In English please Metric means nothing. Inlet 8-10 thou, Exhaust 13-15 thou.

If removing plug leads 1 & 2 does nothing either they're on the wrong way around, or the head gasket has blown between those two cylinders, which if the inlet manifold has failed and allowed coolant to be drawn in, is a possibility because that coolant won't compress, so it has to go somewhere, or it's a fault with the front carb. I think I'd do a compression check for a start.
Click to expand...

Harvey, the die-hard imperial man strikes again! :p

8 thou = 0.2032mm, 10 thou = 0.2540mm, therefore if you want to be "metric-man", I'd say the inlet between 0.21 - 0.25mm (0.20mm = 7.874 thou, not close enough IMHO)

13 thou = 0.3302mm, 15 thou = 0.3810mm, I'd say the exhaust between 0.33 - 0.38mm (0.33mm is 12.992 thou, which I'd say is close enough to 13 thou)

i.e. I'd agree with you on your quoted exhaust clearances in mm, but not quite on your quoted inlet clearances.
 
I'd have a look at the carb too , had some very hard to trace , running problems with my v8 last year when the elbow came adrift of the jet . Hif carbs , don't know what you have Hs /hif but worth a look .
 
Fraser , have I missed an update on your fleet ? I thought you had a yellow P6 and a 75 .Plus a couple of P5's that I see have found new homes
 
Hi Fraser
Check the integrity of the O rings between inlet manifold and the carbs. What you describe recently hit my TC and the problem was a shot sealing ring causing an induction air leak on one carb/inlet. I've put up a diagnostic post in this forum.
Cheers
Keith
 
When I read your post. my first guess too was a problem with your front carb. If you have healthy sparks on 1&2 and your timing is OK (and your valve clearances seems reasonable) I would guess you are perhaps getting a poor mixture on cylinders 1 & 2? Do you have a Colourtune you can put on cylinder 1 or 2 to see what's going on with the engine running?
 
Hi, apologies for the delay in getting re-involved in this post, I've been held up with work.


I've finally got my hands on a compression tester, the compression on the engin varies slightly from cylinder to cylinder, however, they're all sitting on or around 10 bar, there is only about .1 or point .15 or a difference in each cylinder.

I looked at this thread viewtopic.php?f=2&t=11760 to get an idea on the valve timing. I followed the process as my locking point on the camshaft was slightly out. It's inline.

I took the carbs off this afternoon and took apart the floats to check for blockages, there wasn't any, I also checked the fuel pipe, seemed fine.

I had a look at the needle and the jets also and they had little in the way of issues.

I'm running out of idea ideas as to what is causing the problem, when cranking it over earlier I was popping and backfiring through the carbs, which made me think of timing.

Perhaps a simple one but does anyone have to had a photo or a description of the ignition leads and in which order they're wired up? I've not got my workshop manuals to had just now and was wondering if it's something as simple and as silly as that.

Other than that, I'm stumped as to what the problem is...

Thanks

Fraser
 
The way to remember the leads on a 4 cylinder is that when standing at the front of the car, the position on the distributor cap which is closest to you goes to the cylinder which is closest to you. The rotor has an arrow on it indicating the direction of rotation. The firing order is 1 3 4 2.

However the 4 cylinder motor is a difficult to set up right, as you have to have 3 shafts set in the correct position to get the timing correct. Consequently I have seen motors with the distributor cap position furtherest from the front being cylinder number 1, and also the position on the left I think it was, going to cylinder number 1.

I would try on one cylinder only with the lead at different positions and see if it starts to fire on at a particular position. You can then connect on the other leads. I have attached a photo for reference of the distributor on my 2000 which I took prior to replacing it. Since yours is backfiring through the carb that suggest that you have too much advance. Compare it to where yours is and adjust if it is way off.

Have you tried a different condensor. I had one fail within a day of coming out of the box. I would also check the integrity of the insulator which goes underneath the nut on the points. I have had these fail once when fitting a new set of points once, the metal cut through the plastic. I just grabbed the one off the old set and was good to go then.

James.
 

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Hi,

Condensor should'nt be an issue as it's been fitted with an electronic ignition.

I'm having a quick check over of the wiring now, alas battery's starting to run flat now.
 
Cylinder 4, the rear most cylinder.

That said I can't even get it to run, or even fire just now, so I'm not doing too much timing.

I'd set the timing statically, however, the timing marking on the timing wheel is way off.
 
Hi,

I've now got the car running again, however, it is still quite kken to backfire through the carbs. It starts almost instantly from cold, so it would appear that the camtiming has done something, however, it's still quite down on power and when switched off, there is a single loud bang from the exhaust as it is switched off, it sounds almost like a gunshot.

Is this now just a case that the engine now needs re-timed and tuned to compensate for the fact the camshaft is back in line?
 
Have already done the ignition timing, still seems to be running on three cylinders.

I've just whipped the head off. The cylinder head Gasket doesn't look too great, however, considering the pressure it's under I'd be suprised is that was the problem. I have a feeling it's probably valve clearances, however, I've got the head off now and until my new gasket arrives, I'll not really know.
 
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