11 replies to this topic

[crbeasley01]

Hi All,

 

I have a 1992 Mini 998 with dual carbs.

 

A bit of background on how I got to where I am today:

 

While driving one day, the engine overheated (boiling). I pulled over and found that the main belt had been thrown. The belt was already showing signs of wear and had been squealing for a while, so it wasn't completely unexpected, it just failed before I got around to replacing it.

 

Since then, I've been having a hard time getting the car running properly again.

 

After replacing the belt, the engine was still overheating, so I suspected a head gasket issue and replaced the head gasket. The overheating continued, so I wondered if the head had warped or if I had made a mistake during the repair. (I actually had to remove the head a second time after snapping a head bolt during torquing.) I performed one of the coolant combustion gas tests that checks for CO in the radiator, and it came back negative though.

 

Next, I suspected the water pump. This car came from the Middle East and appeared to have been run on plain water for much of its life so the radiator was quite rusty internally, so I replaced both the water pump and radiator.

 

Around the same time, the distributor failed (possibly due to something I did during the head gasket work, though I'm not sure), so I replaced the distributor and ignition coil and then retimed the engine.

 

I also discovered that the secondary electric cooling fan wasn't working. I traced the issue to some wiring and repaired it. As far as I know, however, that fan was not functioning even when the car was previously running well.

At this point, the following components have been replaced:

• Head gasket
• Water pump
• Radiator
• Distributor
• Ignition coil

In addition to the overheating issue, I'm seeing a few other symptoms:

• The engine seems to want to start only as I release the key from the start position, rather than while actively cranking. Not sure if it's related, but it seems unusual.
• There appears to be a slight misfire.
• Once the engine is warm/hot and the choke is off, the idle speed hunts up and down. It will rev up to around 2,000 RPM, drop back down, then rise again. Sometimes it sputters or stalls completely on the low end unless I apply some throttle or pull the choke slightly.

My current thought is that it may be running lean (I recently moved to about 4,500 ft / 1,300 m elevation) or its still the head gasket.

 

Any thoughts on where I should be looking next?

 

Some videos of what I am seeing:
https://drive.google...oUb?usp=sharing

 

 

[sonscar]

Inlet manifold leaking,only one carb working would be my first call.Steve..

[m1n1]

Its not happy is it! i noticed the blue main beam warning light is on when the rpm goes up and off when it goes down.  So there is a wiring issue somewhere - is the engine earth strap connected?

and i think there should be two power feeds to the coil - one from the key and the other from the spade terminal on the starter.   the starter one only gives power when cranking.. so that could poss be the reason for starting when releasing the key.   

[crbeasley01]

Its not happy is it! i noticed the blue main beam warning light is on when the rpm goes up and off when it goes down.  So there is a wiring issue somewhere - is the engine earth strap connected?

and i think there should be two power feeds to the coil - one from the key and the other from the spade terminal on the starter.   the starter one only gives power when cranking.. so that could poss be the reason for starting when releasing the key.   

 

No not a happy engine at the minute. Next step will be looking for a vacuum leak or intake leak I think. 

 

The blue main beam light is because I am missing half the trim on the steering wheel column so the stalk is loose and in the on position. 

 

Good to know on the coil wiring. I'll check that. This thing has some funky wiring that I tried to go together when I put the new coil in.

[crbeasley01]

I noticed the flickering you mean. Interesting. I will have to check into that as it does seem to correlate. Not sure if higher revs just equals the alternator charging more so brighter? Odd for sure

[cal844]

I notice you say the car only starts when you release the key, do you crank the engine on the stop of the start position? If so only rotate the key just enough between run and start to allow the car to fire. My 1980 estate doesn't fire of the key is help on the stop, as soon as I bring the key off the stop it runs.

Hope this helps

[ADRay]

concerning your over heating issue - how’s the thermostat?

[Dashpot Dad]

Is it running a ballast ignition coil? If so it should only get full beans (12v) when cranking and about 9v when running. It sounds almost like yours is wired backwards which is why it only starts as you let go of the key? (just a thought!). If it is running with 12v all the time this will burn out the coil.

 

That misfire sounds very regular to me - I would definitely check your distributor cap and plug leads. Again, if the coil has been over driven then this could degrade the carbon film inside the plug leads. Have you got any others you could temporarily fit to rule this out?

 

Regarding the hunting - this one is very odd. As mentioned above, first port of call would be an air leak at the carbs but the hunting is so severe I am thinking the problem might be elsewhere. Bad engine earths can cause weird issues - is your throttle or choke cable getting hot? I once had a bad engine earth problem and it was trying to earth through the choke cable!! 

[crbeasley01]

Its not happy is it! i noticed the blue main beam warning light is on when the rpm goes up and off when it goes down.  So there is a wiring issue somewhere - is the engine earth strap connected?

and i think there should be two power feeds to the coil - one from the key and the other from the spade terminal on the starter.   the starter one only gives power when cranking.. so that could poss be the reason for starting when releasing the key.   

 

Good call on that wire. Found it disconnected. It starts first crank now.

 

 

Is it running a ballast ignition coil? If so it should only get full beans (12v) when cranking and about 9v when running. It sounds almost like yours is wired backwards which is why it only starts as you let go of the key? (just a thought!). If it is running with 12v all the time this will burn out the coil.

 

That misfire sounds very regular to me - I would definitely check your distributor cap and plug leads. Again, if the coil has been over driven then this could degrade the carbon film inside the plug leads. Have you got any others you could temporarily fit to rule this out?

 

Regarding the hunting - this one is very odd. As mentioned above, first port of call would be an air leak at the carbs but the hunting is so severe I am thinking the problem might be elsewhere. Bad engine earths can cause weird issues - is your throttle or choke cable getting hot? I once had a bad engine earth problem and it was trying to earth through the choke cable!! 

Whats interesting about the hunting is that its it seems to only do it when its warm. When the car first starts and its cold no problem, and then all the sudden it'll start (I noticed it when the temp gauge hit half) and stay around till its off and cools again. 

Will check for earth problems and air leaks. Very possible but pulling the choke in theory should richen it then and alleviate of of the issue but besides revving up doesn't seem to help the hunting?

[crbeasley01]

Engine earth visually looks ok. Nothing obviously wrong with it and it checks out fine on the meter.

 

Found an interesting problem when checking leads. Noticed that when the car was running when I was pushing on the lead to see if it was seated I'd get shocked every time I touched 1, but not on 2,3, or 4. I pulled the 1 and 2 plugs. 1 is the white tip (hot?). 2 is the black tip

 

https://drive.google...iew?usp=sharing

[timmy850]

If you’ve got a 998 you might be better off with BP5ES or BP5E spark plugs. They’re a bit hotter than your current 6 plugs, and they don’t have the resistor in them

If you’re getting shocked when touching the lead it might have a crack in the insulation and be misfiring

[crbeasley01]

If you’ve got a 998 you might be better off with BP5ES or BP5E spark plugs. They’re a bit hotter than your current 6 plugs, and they don’t have the resistor in them

If you’re getting shocked when touching the lead it might have a crack in the insulation and be misfiring

Funny enough the Hayes manual said to go to BPR4ES for 1989+ 998s. Do you think that is too big a jump?