Engine running rough by placing thermostat

[Aranckashi]

Hello all (yes again),

I'm facing another problem with my pinto 2.0, I realized that the previous owner removed the thermostat in the coolant circuit so I was not running the car at full temperature (90°C) but rather almost cold (I thought the temperature gauge was faulty).

I placed a new one and the engine is now at good temperature with gauge needle in the midle ( ..with a stupid satisfaction feeling). The thing is as soon as the engine warms up it becomes rough, rpms swings a bit and vibrations appears.

No sign of this before. Engine was running ok and smooth but at low temperature.
Have any of you ever met this before ?

[Graham]

thermostat could not cause the problem you describe

[katana]

thermostat could not cause the problem you describe

Unless the engine / carb has been set up to work at the low temps . . . . . but it shouldn't be a huge difference.

[Aranckashi]

This morning I turned the crankshaft pulley with spark plugs out to see if there was any resistance at cold. Nothing. I warmed up the engine and did the same. Much more resistance on the ratchet key ! I must add that I have primed the oil circuit before both of the test.

So right after that I removed the timing belt and checked which pulley was that hard. The camshaft pulley was the one. Usually we can feel the force with the resistance of the lobes, but at that time something was wrong. The pulley was stopped by something else each time I tried to turn.
And so to confirm it is the cam problem I have turned the cam pulley again when engine cold. The resistance flew away.

Any idea what is causing that ?

[katana]

Very slight piston to valve contact - it bends just enough to allow rotation?

[Aranckashi]

Very slight piston to valve contact - it bends just enough to allow rotation?

I don't know at what position was the crankshaft but the cam turns without touching the pistons. Probably had no TDC on all pistons with luck.
But on stock pinto engine I often heard that if the timing belt breaks the valves will be alright.

[alladdin]

sounds like cam bearing issue , expanding when hot and pinching cam check end thrust plate too ?

[Aranckashi]

sounds like cam bearing issue , expanding when hot and pinching cam check end thrust plate too ?

Yeah it seems that it comes from there. Also I have read from a post that the cylinder head can warp when hot.

Good idea about the end thrust plate, I will check that too.

[Aranckashi]

Ok today the cylinder head has been removed in order to check camshaft specifications. Everything seems alright on cam bearings, I get 0.004 inch (0,1mm) of clearance on each.

So I've checked flatness of the block and cylinder head to see if the problem can come from there. Have maximum of 0.003 inch difference on the cylinder head and 0.0035 inch on the block.

I have searched flatness tolerance for pinto engine with no luck.
Does anybody knows what to expect please ?

[Aranckashi]

thermostat could not cause the problem you describe

Graham, may I have your thought on this please ?

Got 0.003 inch flatness difference on cylinder head and 0.004 inch on the block max. Is it critical ?

[Graham]

Graham, may I have your thought on this please ?

Got 0.003 inch flatness difference on cylinder head and 0.004 inch on the block max. Is it critical ?

thats way too much

[Aranckashi]

thats way too much

Thank you. A thicker head gasket after rectifications will be enough ? Any other suggestion to get the job done ?

[Graham]

Thank you. A thicker head gasket after rectifications will be enough ? Any other suggestion to get the job done ?

thicker gasket wont fix such an uneven surface, you need to have teh block and head refaced/skimmed to get them flat and true, i dont know if this is actually your issues, but its something you need to put right if you want headgaskets to last

[Aranckashi]

thicker gasket wont fix such an uneven surface, you need to have teh block and head refaced/skimmed to get them flat and true, i dont know if this is actually your issues, but its something you need to put right if you want headgaskets to last

My current issue is camshaft turns with hardness when engine get to temperature. No problem when cold from start. Cam and bearings are all in specifications, end thrust plate too.
So I'm now trying to eliminate this problem pointing the flatness of the block/head.

What you said is what i'm planning to do but considering I need to remove around 0.007 inch in total, should I install a different head gasket with larger thickness or I should be fine ?

[katana]

Although - with a cast iron head - warping or a twist is rare it could explain your issue ie. when cold the tolerances stack up to give acceptable clearances to allow rotation but as heat builds, the tolerances tighten and start to bind? Or even the cam could be bent ?

[Aranckashi]

Although - with a cast iron head - warping or a twist is rare it could explain your issue ie. when cold the tolerances stack up to give acceptable clearances to allow rotation but as heat builds, the tolerances tighten and start to bind? Or even the cam could be bent ?

That's the only reason I see.
Camshaft has been checked it's straight. I need to skim about 0,2 mm and I don't know if I can place a new 1,3 mm Victor reinz gasket without changing compression ratio.

[katana]

If the head is warped enough the cam binds then facing head and block won't help the cam situation - only line boring will do that! So either lots of checking or buy a different one!

[Aranckashi]

That's true. Arff !
The cylinder head is warped by 0,07 mm, that's 0,02 mm off the specifications. So what about decking the block only and taking the risk to torque the head on ?

Or honing the center cam bearing just under the float limit spec (0,1 to 0,2 mm) ?

Yes this is the wallet talking

NB: All is stock - no racing. This is my daily car.

[Forest_rallying]

That's true. Arff !
The cylinder head is warped by 0,07 mm, that's 0,02 mm off the specifications. So what about decking the block only and taking the risk to torque the head on ?

Or honing the center cam bearing just under the float limit spec (0,1 to 0,2 mm) ?

Yes this is the wallet talking

NB: All is stock - no racing. This is my daily car.

I doubt very much that it’s head Face that’s giving you your problems, but if it’s only a bog standard engine it won’t be that difficult to find a replacement cylinder head. There’s never a cheap way to fix an engine properly, you have to dig deep into your pocket (wallet).

[Aranckashi]

I doubt very much that it’s head Face that’s giving you your problems, but if it’s only a bog standard engine it won’t be that difficult to find a replacement cylinder head. There’s never a cheap way to fix an engine properly, you have to dig deep into your pocket (wallet).

I had a doubt too but after few others checking, I'm still pointing the warpage face. Clearance at the center cam bearing is all the way up. I have tried to slip a aluminum foil (0,01mm) all around between the cam/bearing and no clearance at all in lower part. The camshaft is free to turn but I think it's just under the limit.
So I'm gonna take the risk to resurfacing the bloc only and torque the head as it is. In the worse case it will cost me a gasket and torx bolds again.

Trying to find another head is not difficult as you've said but there is chance that I will find like cracks or other things. And yes after having rebuilted the engine I'm aware of that, money is flying.

[onecamohv]

its rare, but did you check the cam itself for runout ? I've not seen it, but I've heard of bent cams before.

[Graham]

its rare, but did you check the cam itself for runout ? I've not seen it, but I've heard of bent cams before.

agree, not on a ford, but i have had bent cams too

[Aranckashi]

its rare, but did you check the cam itself for runout ? I've not seen it, but I've heard of bent cams before.

Yep, did twice on V blocks with a dial indicator. Perfectly straight.

[Aranckashi]

So a bit of an update. I'm about to start the engine again after the block has been decked (0,1mm). The thing is during oil priming I don't have a flow at the cam spray bar, it spits only. I was running the drill for +2 mins nothing changed, and I hear the pump (?) sucking air. Also, by removing the spray bar the oil flows but still with air holes. I'm pretty sure the circuit is primed but something is going on with the pump, wich is new.

I'm now thinking of my camshaft problem not turning well when engine is warm. Could it be a lack of oil at the top when thinner ?

[Graham]

So a bit of an update. I'm about to start the engine again after the block has been decked (0,1mm). The thing is during oil priming I don't have a flow at the cam spray bar, it spits only. I was running the drill for +2 mins nothing changed, and I hear the pump (?) sucking air. Also, by removing the spray bar the oil flows but still with air holes. I'm pretty sure the circuit is primed but something is going on with the pump, wich is new.

I'm now thinking of my camshaft problem not turning well when engine is warm. Could it be a lack of oil at the top when thinner ?

it could be lack of oil, even on a battery drill a pinto chucks loads of oil out the spray bar and will usually achieve 60 psi.

if i were you my first port of call would be check the gasket between the oil pickup and pump

[Aranckashi]

it could be lack of oil, even on a battery drill a pinto chucks loads of oil out the spray bar and will usually achieve 60 psi.

if i were you my first port of call would be check the gasket between the oil pickup and pump

Strange thing is when I'm blocking the hole that feeds the spray bar with my finger, the pump(?) is sucking air but if I do the same at the hole feeding the oil filter I get quite a good pressure and no air sound. It would be interesting to see the lubrication system to understand.

That's a good info about the pickup gasket. I will have a look.

And yeah that is something I can see on start up with a 20w50, I have to give a little throttle as soon as the oil gets picked.

[Graham]

Strange thing is when I'm blocking the hole that feeds the spray bar with my finger, the pump(?) is sucking air but if I do the same at the hole feeding the oil filter I get quite a good pressure and no air sound. It would be interesting to see the lubrication system to understand.

That's a good info about the pickup gasket. I will have a look.

And yeah that is something I can see on start up with a 20w50, I have to give a little throttle as soon as the oil gets picked.

your sucking sound might not be sucking at all, oil sqeezeing out the crank bearings makes a kinda sucking sound

[Aranckashi]

your sucking sound might not be sucking at all, oil sqeezeing out the crank bearings makes a kinda sucking sound

Main bearings are new. I always had 25-30 psi pressure at idle and around 80 psi driving. But, it was with thermostat off so engine was running cold.

Sounds like I need to take this problem more seriously.

[Aranckashi]

Unbelievable ...

Graham, you spotted it right