Starting problems after changing head gasket

[PatrickHarnett]

I knew my 2002 Fabia had a blown head gasket but continued to run it locally without any problems. Keeping an eye on the oil and water.

 

Finally one day it wouldn't start.

 

I towed it home and changed the head gasket. Pressure tested the head and re-skimmed it just in case. I readjusted the tappets. In dismantling I found that the thermostat had become detached from its housing the two tabs that hold it in had broken off. So temporarily I put the housing back without the Thermostat.

 

Now it is all back together it makes an effort and tries to start but just won't start without a foot on the accelerator. It wont idle properly and then it just dies after a while.

Oddly when the brake vaccum pipe is disconnected from the inlet manifold it will start more easily but obviously runs very roughly.

 

Have I forgotten something? Any ideas what could be the problem?

[sepulchrave]

It does sound like there could be a big leak in the inlet manifold/pipework somewhere. Did you reconnect all the sensors properly?

[puddy]

Sounds like its running too rich . Likes the extra air with the vacuum pipe open. But probably a cam timing issue with a home  mechanic,  no offence.

Cheers puddy  

[sepulchrave]

1 hour ago, puddy said:

Sounds like its running too rich . Likes the extra air with the vacuum pipe open. But probably a cam timing issue with a home  mechanic,  no offence.

Cheers puddy  

 

1.4 MPI is a pushrodder, how does lifting the lid change the timing please? No offence.

[puddy]

Where the hell does it say  what engine is in it ? 

Thats why i said PROBABLY fyi . 

No offence.

[puddy]

Just remembered why i dont normally get involved with giving advice on forums .......

Edited 11 March, 2018 by puddy

[sepulchrave]

10 minutes ago, puddy said:

Where the hell does it say  what engine is in it ? 

Thats why i said PROBABLY fyi . 

No offence.

 

In the sidebar next to the post on the OP's sig.

 

None taken.

[bigjohn]

15 hours ago, PatrickHarnett said:

I readjusted the tappets

 

Why did it stop starting in the first place?- even with a bad head gasket it would usually start on a couple of cylinders or so, it doesn't normally fail on all cylinders unless you've had a major overheating incident. You may have another fault unrelated to the head gasket.

 

Go back to first principals, some seem rather obvious but worth checking:-

 

Are you getting a good spark on all cylinders (use an old plug to check each one in turn) - could be the coil pack if not

Presume  it has enough petrol in (yup - had this issue in the past , was a faulty tank sensor!)

 

Just in case do a compression test(if you have a tester) - On a push rod engine if you have misset the tappets the valves could be held slightly open. Especially important after a head skim and a new head gasket as the distance between the top of the cam follower to the base of the rocker shaft may have changed. The compression test will also confirm that the head gasket has been fitted OK (On a Cortina mkII pushrod years ago I damaged the gasket slightly on fitting that caused a raised area on the top of one of the cylinder walls - that didn't work well - fitted a new gasket and all OK)

 

Could be an air leak especially where the inlet manifold is bolted to the cylinder head

 

 

 

[TMB]

The tappets are hydraulic and not supposed to be adjusted after only a head gasket change. The setting is a preload, there is no clearance.

 

From Skoda workshop manual...

 

Quote

The basic setting of the hydraulic valve clearance compensation must not be carried out again, if only the cylinder head gasket is replaced.

 

 

Edited 11 March, 2018 by TMB

[TMB]

Here's the setting procedure so you can check you've got it right...

 

https://workshop-manuals.com/skoda/fabia-mk1/drive_unit/1.0/37;_1.4/44;_1.4/50_kw_mpi_engine/engine_cylinder_head_valve_gear/repairing_cylinder_head/basic_setting_of_hydraulic_valve_clearance_compensation/

[moley]

Did you re seat the valves? It could be an inlet valve not seating correctly. Compression test would check this.

[PatrickHarnett]

58 minutes ago, TMB said:

The tappets are hydraulic and not supposed to be adjusted after only a head gasket change. The setting is a preload, there is no clearance.

 

From Skoda workshop manual...

 

 

 

The head was skimmed so I think the tappets do need to be adjusted.

[PatrickHarnett]

58 minutes ago, TMB said:

Here's the setting procedure so you can check you've got it right...

 

https://workshop-manuals.com/skoda/fabia-mk1/drive_unit/1.0/37;_1.4/44;_1.4/50_kw_mpi_engine/engine_cylinder_head_valve_gear/repairing_cylinder_head/basic_setting_of_hydraulic_valve_clearance_compensation/

Thanks for this - yes I followed this procedure.

[TMB]

OK, should be all good then.

 

I wouldn't say a head skim would necessitate tappet adjustment though. The lifters will easily compensate for that.

[bigjohn]

As I mentioned before drop back to first principals - ie have you got a spark on each cylinder, fuel, air, compression? especially checking the inlet manifold gasket and coil pack

 

 

[sepulchrave]

31 minutes ago, TMB said:

OK, should be all good then.

 

I wouldn't say a head skim would necessitate tappet adjustment though. The lifters will easily compensate for that.

 

A skim would close up the clearances on a pushrod engine so I would loosen them off slightly myself, especially since they tend to tighten anyway as the engine wears due to valve head/seat recession.

[bigjohn]

2 minutes ago, sepulchrave said:

 

A skim would close up the clearances on a pushrod engine so I would loosen them off slightly myself, especially since they tend to tighten anyway as the engine wears due to valve head/seat recession.

 

As mentioned above it looks as though this engine has hydraulic tappets (which I didn't know, my experience in pushrod engines is with Ford, Austin/Morris and Hillman). It's still worth a compression test though just in case there is something not quite right.

[sepulchrave]

25 minutes ago, bigjohn said:

 

As mentioned above it looks as though this engine has hydraulic tappets (which I didn't know, my experience in pushrod engines is with Ford, Austin/Morris and Hillman). It's still worth a compression test though just in case there is something not quite right.

 

I know, but hydraulic tappets don't help if the clearance is too tight, they actually make it worse.

[bigjohn]

4 minutes ago, sepulchrave said:

 

I know, but hydraulic tappets don't help if the clearance is too tight, they actually make it worse.

 

They should settle after a few minutes as shown in the setting procedure. Saying that some engines do have problems with this - eg Peugeot 104 1.5 diesel couldn't start warm as the valves self adjusted themselves slightly open with the heat expansion.

 

I was once trying to start someones 1300 pre crossflow MKII Cortina many years ago after it had been parked up for a while. It popped and banged but just wouldn't go it had fuel and spark on all four in the correct order (I always took rocker cover off to check looking for the opening inlet valve before the compression stroke then expecting a spark). Compression test showed OK on one cylinder and nearly zero on the other three - Houston! I took the head off to have a look and found that valves had stuck open through lack of movement for a few months. Quick stripdown, clean and new vlave seals did the trick - instant start when head re-fitted!

 

Just in case - any codes logged - possibly modern technology may help here?

 

I'm still not convinced it was the head gasket that stopped it from starting in the first place

[PatrickHarnett]

13 hours ago, bigjohn said:

 

They should settle after a few minutes as shown in the setting procedure. Saying that some engines do have problems with this - eg Peugeot 104 1.5 diesel couldn't start warm as the valves self adjusted themselves slightly open with the heat expansion.

 

I was once trying to start someones 1300 pre crossflow MKII Cortina many years ago after it had been parked up for a while. It popped and banged but just wouldn't go it had fuel and spark on all four in the correct order (I always took rocker cover off to check looking for the opening inlet valve before the compression stroke then expecting a spark). Compression test showed OK on one cylinder and nearly zero on the other three - Houston! I took the head off to have a look and found that valves had stuck open through lack of movement for a few months. Quick stripdown, clean and new vlave seals did the trick - instant start when head re-fitted!

 

Just in case - any codes logged - possibly modern technology may help here?

 

I'm still not convinced it was the head gasket that stopped it from starting in the first place

Yes you are probably right there is most likely another problem. But the gasket was definitely gone and I thought it was time to do it, I didn't realise that I would have problems finding what was wrong. I think my rather dated mechanical experience is showing.

Your suggestion about the basics is a good one. There is fuel. The car fires and can run so there is a spark. The gaskets on the inlet manifold have been renewed, I think it would be hard not to fit them correctly (the symptoms seem more to do with not enough air rather than too much, it needs accelerator to go) . Compression - I don't have a meter (and my assistant is at school today). I used to do it just by putting a thumb over the plug hole. I have turned the engine by hand and I can feel quite a good resistance so there is compression somewhere!

 

How about the fact that the thermostat has become detached? I have had to remove it completely from the housing the tabs holding it in seem to have broken.

 

[sepulchrave]

It is a good idea to replace the thermostat, they're not expensive and not having one will negatively impact the fuel economy and warm-up time.

[PatrickHarnett]

Yes I will certainly change the thermostat, its a temporary measure I didn't want any bits loose in the system.

[bigjohn]

3 hours ago, PatrickHarnett said:

 

Your suggestion about the basics is a good one.

 

re:-The car fires and can run so there is a spark

 

Fires on four cylinders? I think this engine has a wasted spark coil pack - so if one part has failed (or is failing) it would tend to run on two cylinders, usually really shows up as the weather turns cold/damp.

 

 

re- the symptoms seem more to do with not enough air rather than too much, it needs accelerator to go

 

Possibly not - it there is too much air and not enough fuel then hitting the throttle will add fuel making it sort of go but it wont tickover (Simialr to when the carb insulator block used to crack on  VW polo causing a large air leak. You could start and rev the engine but it wouldn't tickover). You have to think where the injectors sit compared to a potential air leak. You will struggle to tickover if way too weak or way too rich. If too rich you normally eperience "hunting" before the engine dies.

 

Do the plugs smell of petrol when you remove them?

 

 

 

 

 

 

 

Edited 12 March, 2018 by bigjohn

[PatrickHarnett]

There are sparks at all four plugs.

I cant see any obvious places where there could be an air leak. Plus it starts easier when the vacuum pipe is off! (introducing an air leak effectively)

 

True the plugs do not smell of petrol.

[bigjohn]

Have you disturbed a temperature sensor, or engine speed sensor or camshaft position sensor whilst sorting the head?