15 replies to this topic

[mookalarni]

Hey everybody, 

 

long time lurker, I require a bit of assistance please...

 

So I've only just got my car back on the road after 10 years of dry storage, few carb problems initially but then running reasonably for a few weeks although felt a little hesitant and underpowered. It has a 'stage 1 kit' fitted, maniflow system and cone K&N, has previously been dyno'd and tuned was running well afterwards albeit a little rich, no other engine mods. 

 

I took it for a rather spirited drive/italian tune and it was responding well once warmed up, parked up and thought nothing of it. Later that day I went out again and the temperature indicator was starting to creep up towards the high mark and it was running really rough, I limped it home and parked it up, I assumed it was just idling in traffic too long. 

 

Went to start it the next day and it was running really poorly, fired up okay and could keep it running if you held the accelerator down but the choke was killing it. Left it for the day and now it fires, starts and then dies immediately, regardless of accelerator/choke input. 

 

I pulled the float bowl apart and checked that, all appears okay. Mechanical pump feeding okay into catch jar. Carb could probably do with a service/overhaul. Dashpot full of correct oil. The radiator where previously at a good level has now dropped below the matrix. 

 

I did a compression test just now (coil lead disconnected,what, all plugs removed) and have these figures:

 

Cylinder 1 - 145

Cylinder 2 - 120

Cylinder 3  - 160

Cylinder 4 - 160

 

Ran it again:

 

Cylinder 1 - 145

Cylinder 2 - 115

Cylinder 3 - 145

Cylinder 4 - 155

 

I put a tablespoon of oil into Cylinder 2 and retested that one in isolation, 145.

 

I'm inclined to think this is a head gasket issue, it's overheated and lost coolant and now compression figures down between cylinder 1 and 2, although I'm not sure whether it would respond to oil in the cylinder if this was the case. 

 

Could anyone advise? What do I need to do next / focus my efforts towards? I have most tools and willing to give anything a go. Planning to get a gasket kit and pull the head off at the weekend but will welcome any suggestions. 

 

Thanks all 

 

 

[Earwax]

I would search for some other possibilities before taking the head off. 

 

You probably have already but

 

Check plug fouling, leads and exclude dirty fuel ( laid up for a period of time) - also check fuel cap venting ok and restricted air filter.

 

Check dizzy hasnt loosened.

 

Etc good luck - I wouldnt absolutely conclude a 120 reading is a head gasket - fingers crossed

[68+86auto]

I wouldn't worry about the compression value itself.

 

What is more concerning is the coolant level. Firstly check the oil level and that it isn't mixed with water. Then run the engine and look for bubbles in the radiator filler neck. If yes then it's probably a head gasket or head. If you can't see bubbles then that doesn't confirm that the gasket is good but make sure to do one of the following to determine if it is bad before removing the head. You can either use a cooling system pressure tester to test if it's being pressurised by combustion gasses or alternatively use an exhaust analyser to check for combustion gasses in the radiator. If neither of those options are available then you can try to put a disposable glove over the radiator filler neck (cap removed) and rev the engine. see if the glove inflates, if it does then you have a gasket or head issue.

 

I wouldn't go to head gasket testing if you hadn't mentioned the coolant level dropping.

 

Once the head gasket is confirmed as good, you need to check the ignition system BEFORE touching the carb. The carbs can go wrong but it's unusual compared to the ignition system. Do you have points or electronic? Is the condenser good? is the dwell (gap) good? Is the timing good?

[Steam]

If you ran it with old fuel getting into the cylinders the valve stems could be gummed up from the old fuel causing a valve to stick, hence low compression. Recheck the valve clearances amd clean the fuel system and fresh fuel.

[mookalarni]

Thanks all for the advice and reassurance, good points to start on. I initially felt like it was an ignition/fuel problem and then decided to do a compression test anyway then I was just adding up all the other symptoms and arrived at head gasket. 

 

Dizzy felt tight so I don't think it's moved at all. I'll put a new set of points & condensor in and set those, there is slight scoring on the dizzy cap so probably just fit new rotor arm and cap to be safe and then check the valve clearances. 

 

It's had 3 tanks of super unleaded through it since I first got it back on the road so I'd be surprised if it was bad fuel, it was stored empty - but it hasn't got an inline fuel filter fitted, that's on the to do list also. 

 

Currently not running at all so can't check the cooling system for bubbles. Oil level appears normal and no change from when I checked it last week. 

 

I'll double down on the ignition checks and simple bits first and then go from there, if I can get it started I'll start radiator checks ect. 

[gazza82]

Dizzy felt tight so I don't think it's moved at all. I'll put a new set of points & condensor in and set those, there is slight scoring on the dizzy cap so probably just fit new rotor arm and cap to be safe and then check the valve clearances.

Don't just go whacking new parts on ... in a lot of cases OLD parts are better than new ... you could be adding to your issues so diagnose them first and only change ONE part at a time, otherwise you will never know what was the cause either.

[sonscar]

Is the choke sticking on?float chamber flooding?just thoughts,Steve..

[mookalarni]

 

Dizzy felt tight so I don't think it's moved at all. I'll put a new set of points & condensor in and set those, there is slight scoring on the dizzy cap so probably just fit new rotor arm and cap to be safe and then check the valve clearances.

Don't just go whacking new parts on ... in a lot of cases OLD parts are better than new ... you could be adding to your issues so diagnose them first and only change ONE part at a time, otherwise you will never know what was the cause either.

 

fair point, probably a bit too eager to just replace stuff hoping that it will work. The dizzy cap has scoring on the contact points inside, at what point would you look to replace that or rotor arm? What would suggest a bad condensor or points?

[mookalarni]

Is the choke sticking on?float chamber flooding?just thoughts,Steve..

choke appears to be operating freely, float chamber clean and valve appears to be operating 

[Cooperman]

It's very easy and quick to remove the head on a 998. Why not remove it, check for bore wear, check the valves and re-lap then. That way you'll know it's not a head or gasket issue.

Then check the distributor. I would remove it, check for wear in the shaft, re-lube the bob-weights, fit new points, rotor arm and condenser and set the timing as accurately as poss when re-fitting it.

Whilst the carb is off, clean it all out, check the float valve and that sure the piston drops smoothly.

When all reassembled, start it up and set the tick-over, Make sure it is timed optimally by moving the dizzy until it's running well. You can use a strobe light, but it's not essential'

Once warm, check the mixture and adjust it as required.

Personally I would fit new plug leads and plugs.

 

That's all straightforward and we are all here to help.

[mookalarni]

It's very easy and quick to remove the head on a 998. Why not remove it, check for bore wear, check the valves and re-lap then. That way you'll know it's not a head or gasket issue.

Then check the distributor. I would remove it, check for wear in the shaft, re-lube the bob-weights, fit new points, rotor arm and condenser and set the timing as accurately as poss when re-fitting it.

Whilst the carb is off, clean it all out, check the float valve and that sure the piston drops smoothly.

When all reassembled, start it up and set the tick-over, Make sure it is timed optimally by moving the dizzy until it's running well. You can use a strobe light, but it's not essential'

Once warm, check the mixture and adjust it as required.

Personally I would fit new plug leads and plugs.

 

That's all straightforward and we are all here to help.

Thank you, comprehensive and helpful. 

 

I'll get it all to bits at the weekend and see what I find, I think I'll go through ignition, then carb then head off as last option. This sounds more ignition/fuel given the other replies but I think head is going to have to come off at some point even if I get it running again. Anything else sensible to do whilst that's off or just valves and gaskets? 

[Cooperman]

I once did a comprehensive resto of an Innocenti which took around 10 months.

After completion I started it and whilst it would tick-over, as soon as I tried to put the engine under normal driving loads it would run roughly and lack power.

After taking off the carbs and re-cleaning/checking them (again), I swapped the distributor cap and leads with my Cooper 'S', but that made no difference.

I fitted a different coil and changed the condenser. Still no improvement.

In the end, I took the distributor out of the car and stripped it. It turned out that the bob-weights at the base of the dizzy were gummed up. After cleaning with brake & clutch cleaner and lightly oiling with 3-in-1 it ran perfectly.

As stated above, you need to check and set everything.

With the Innocenti, I had stripped the engine, fitted new piston rings and new ex. valves plus valve guides, etc., so I knew all was good with the top end, cylinder compressions, etc.

[mookalarni]

I once did a comprehensive resto of an Innocenti which took around 10 months.
After completion I started it and whilst it would tick-over, as soon as I tried to put the engine under normal driving loads it would run roughly and lack power.
After taking off the carbs and re-cleaning/checking them (again), I swapped the distributor cap and leads with my Cooper 'S', but that made no difference.
I fitted a different coil and changed the condenser. Still no improvement.
In the end, I took the distributor out of the car and stripped it. It turned out that the bob-weights at the base of the dizzy were gummed up. After cleaning with brake & clutch cleaner and lightly oiling with 3-in-1 it ran perfectly.
As stated above, you need to check and set everything.
With the Innocenti, I had stripped the engine, fitted new piston rings and new ex. valves plus valve guides, etc., so I knew all was good with the top end, cylinder compressions, etc.

Plenty to go by there, I appreciate the advice you all offer here, plenty of years of experience. I'll report back after this weekend once I've had a good go at the above.

[Steam]

If the oil you put in the cylinder improved the compression it is unlikely to be a head gasket causing low compression. If you have a good strong spark at each plug and the timing is somewhere close to correct then it will probably be fuel supply to the carb. Check for fuel at the top of the jet You could use a straw placed on top of the jet and blow back to the float bowl to prove the jet supply tube is not blocked.

[mookalarni]

Well, thanks to those that gave advice, it's sorted now. Kind of....in typical mini fashion one problem has become several problems. 

 

So I pulled the air filter off the carb, all looked okay, piston moving freely with damper out and landing with a thud, choke operating well and returning to normal, gave it all a slight clean and re-assembled and filled the dashpot again. Opened the float bowl, the valve appears to be working okay and not sticking, I can't get the retaining pin out of the float to remove fully but it's moving in and out when you touch it. Did the straw test on the jet, not coming through to the bowl. The bottom of the float bowl had that sort of sandy paste, I sucked the fuel out with a syringe and then cleaned it all out, it was all sludgy brown. Blew through the jet and it was now going through the float bowl okay. 

 

Re assembled it all and put in a new set of gapped plugs. Eventually started up once the fuel had pumped through. 

 

Ran it for a good 10 mins or so, idling well and temperature reading normally so took it out for a drive, running really well through the rev range. Gave it a bit of a boot thinking it was probably just blocked jet and a good run through would do it some good. 

 

Arrived back at home and decided to check all my electrics. I noticed that went I turned my lights on, the rev counter stopped working, just fell to 0, once I turn lights off the rev counter kicks in again. When the lights are on and the rev counter stops, the engine temperature then begins to climb up towards the red, lights off and rev it a bit and it falls down quickly. 

 

So I think that the non starting/running issue was probably a blocket jet and/or crud in the fuel lines, I'll get an inline filter in ASAP.

 

Apparently there is a new electrical issue to contend with though, any ideas? I put a new 4 fuse block and hazard/indicator relays on last week as they were all corroded and I lost everything off fuse 1. So there's dim/dip interfering with the rev counter and then the engine temperature "going up" as a result, I think the "overheating" was this electrical issue.