Club 80-90 Forums

My long suffering MV engine owners, I'm coming to the end of my tether! My syncro is running like a bag of poo poo and I'm out of ideas. Before I sack off the injection system for a single carb, I'm going to have one final attempt at smooth running once again.

Engine: 1991 syncro 2.1MV, running LPG. SYMPTOMS OCCUR ON BOTH FUELS!
The symptoms: loss of power both at acceleration and traveling along. Hills are almost not doable and even pulling off on a cambered road can be difficult. I do however, get bursts of power. Running very hot, but not on the dash thermostat gauge, there is just the smell of burning coolant (it also bubbles in the tank). I also get smoke from the dust and dirt on the exhaust shield burning. I am also returning HALF the MPG I was before this problem developed.

My thoughts: thermostat? Wiring? Idle stabilisation? Throttle position sensor?

I have: changed the temp 2 sender, changed the air flow meter, checked all earths.

Please help!!!!!!!!!!

Thanks

It also stays revving after I come to a stop, and revs only go if I bring the clutch up to bite

OK...so it's running running very hot. Coolant bubbles means it is basically boiling somewhere inside the engine.
My thinking is that your stat has failed shut, so coolant isn't curculating properly, which is why the dash gauge is reading normally so...

Change the 'stat first for a quality item. Not a fun job, you'll probably have to replace the housing too as the bolts will be siezed in to the drillings in the housing and probably the head too. Get the engine warmed up before starting, it will give you a fighting chance. Be ready with a M6 star drive to belt into the bolts, they will rusty. if this fails, you will need some Irwin nut busters. Awesome tools, they will loosen the undo-able!

Then check the bleed lines aren't full of gunge/mud/silt/rad-weld etc. The little one on top of the 'stat bonnet is a favourite, had one that was full up for the entire length, but the steel rail was clear.

Let me know what you find.

Ian

PS broken bolts in the syncro stat housing aren't the end of the world, I can recover them for half the price of a new replacement with s/s helicoils, assuming it isn't badly corroded.

Not up with the 2.1 engine but if the system is like the mk2 golf digifant then the blue coolant temp sender on the golf gives all these symptoms when it fails as the ecu gets all it's info from it and it over fuels cause it thinks the engine is still in warm up mode (choke) ,worth a try if yours is the same

I think that he's already tried that. If the stat is duff then the ecu won't be getting the correct values anyway. There's no way it could be running that bady on a rich mixture, if anything it would run cool and very sooty. Classic overheating problem.

Thanks guys, particularly Silverbullet.

I've replaced the temp 2 sender and it's wiring to the ECU and AFM, so my next guess was thermostat. I have a quality one from Brickwerks and a new top, but not the bottom bit so fingers crossed! I've also ordered all the coolant I need, so that will be getting drained out in the morning and all pipes checked ready for a fresh load.

I've been loosing enough coolant for the red light to flash about once a week, which has been escaping from the coolant level sender (so a new O ring ordered) and the joint at the radiator pipes.

Big day tomorrow!

Oh, and again, shout out to Brickwerks for their insanely fast turnaround!

Watch those coolant header tank sensors, they crack in the seal groove with old age!
Just make sure that you tackle the 'stat housing with some heat in the engine before draining down. It all helps!

silverbullet wrote:Watch those coolant header tank sensors, they crack in the seal groove with old age!
Just make sure that you tackle the 'stat housing with some heat in the engine before draining down. It all helps!

it's a new tank, as the old one has cracked there soon after I bought the van! Cheers for the tips!

chuckle-bus-tom wrote:

silverbullet wrote:Watch those coolant header tank sensors, they crack in the seal groove with old age!
Just make sure that you tackle the 'stat housing with some heat in the engine before draining down. It all helps!

it's a new tank, as the old one has cracked there soon after I bought the van! Cheers for the tips!

It's the sensor, not the tank, that Ian was saying cracks with age.

Wychall wrote:

chuckle-bus-tom wrote:

silverbullet wrote:Watch those coolant header tank sensors, they crack in the seal groove with old age!
Just make sure that you tackle the 'stat housing with some heat in the engine before draining down. It all helps!

it's a new tank, as the old one has cracked there soon after I bought the van! Cheers for the tips!

It's the sensor, not the tank, that Ian was saying cracks with age.

OK, thanks, I'll check for that when its out to be sure.

.. has the lambda sensor been removed from your setup?? if it is still wired in, when was it last changed/checked??
d.

id also check the water pump is working correctly......pull the spark plugs out and have a look at the colour white/grey is running lean and could also cause your overheating

mark

TheProf wrote:.. has the lambda sensor been removed from your setup?? if it is still wired in, when was it last changed/checked??
d.

Lambda was new 2 years ago when LPG done. I recently disconnected to eliminate it from the problems (with no change in running). It's currently disconnected.

mark wrote:id also check the water pump is working correctly......pull the spark plugs out and have a look at the colour white/grey is running lean and could also cause your overheating

mark

I'm sure the water pump is ok or I would be properly over heating. Here's what the plugs look like anyway (bear in mind I run on LPG)


And here's my main problem: 2 snapped nuts getting the thermostat out

"pooh". I'm really in a spot now. The two Allen bolts are a no-go. Attempting to drill out the snapped bolts in the stat housing with it in situ is now my only option.

Other than flicking a match at the van and claiming on my insurance.