Blown Head Gasket?

[rhymeface]

EDIT: changed the title as it might prove more helpful for people experiencing similar problems.

The car is a 1988 Nissan Sunny N13 - has a 4 cyl SOHC 1.6 petrol engine.

Had a few issues with this engine over the past few months since winter and now it's has just developed a new one.

Bit rough on starting up and idling.

Then when I hit the road there was this noticeable banging sound that sped up with the engine. Only there on acceleration. Car also judders and lurches on acceleration.

Noticeable loss of power as well.

Where to start??

[Deleted]

Could be all sorts of things at this point. From dire to minor. I'd probably try to get a bit more detail down about the issues, and also more info about your car.

Is it fuel injected or on carbs? Is it original/standard or modified in any way?

Whats your oil pressure like?

Has it recently had any work that may have changed anything?

Is the knocking a harsh, metallic physical knock (such as a big end knock) or could it be more like clutch judder or a failed gearbox mount?

When you start it up and it's rough, does it try to cut out? Is it starved of something or could you have an air leak at the servo or intake manifold? Is the car blowing any smoke that it doesn't usually?

Can you still drive it and will it reach higher revs?

Maybe take a video of it running and try to catch the knocking noise.

[Deleted]

I've just read back through your previous posts. Ignoring the description of a knocking noise ... In my experience whenever anyone says "knocking noise" on a car forum it's very each to reach for the "Your big end's gone mate" drama, when we all have a different interpretation of what actually constitutes a knocking noise.

If it's really pronounced then that's the issue and it could be serious. Otherwise it could just be a byproduct of a temporary fault.

So it seems over the last X months you've changed the intake manifold, put a copy of a Weber DGEV on (32/36? and an electronic choke?) and you've tackled the coolant system.

Based on this, my first guesses would be (and again I'm ignoring the "knocking" reference here) that maybe you've developed a leak at the intake manifold, or the servo is faltering (mine went earlier this year and your description above is very similar to what I experienced) or there's something gone wrong with the carb.

One thing you can try is to remove the servo hose from the servo (it runs from the servo to the intake manifold) and block it off with a bolt, then see of the car runs easier. Check your brake fluid level and see if that's dropped significantly too. If you do disconnect your servo hose beware the brakes will probably feel very different!

Have you overtightened the carb and it's started to warp the base allowing air to seep in?

Have you checked the choke to make sure it fully opens and closes as it should?

If it's stuck ajar and can't operate properly it will make starting groggy and will also make running lumpy once worm.

Maybe as a stage 1 you might want to get the car idling without the air filter on and blast carb cleaner into the carb throat, and spray WD40 around the carb base and the intake manifold while its running to to see if that changes the idle revs. Also inspect all the choke and throttle movements and give them a clean too.

Maybe your timing has slipped and you need to get the timing gun on it.

Maybe your vacuum advance pipe has come off, split, or has a little hole in it.

Press on all of your HT leads and king lead. Maybe you haven't reconnected them properly after doing something. Maybe you've got a badly fouled plug and you're running one three cylinders or you have a dirty spark.

Maybe your coil is breaking up.

Maybe you have oil leaking onto the clutch assembly. Does it seem to need much higher revs to make the car get up to speed?

It could be a tonne of things really.

It would be better to assume/hope the knocking is merely a by-product of an engine not running right... unless it's a really dramatic knocking which cannot be ignored.

[rhymeface]

Jun 10, 2018 10:14:02 GMT @quatermass said:

I've just read back through your previous posts. Ignoring the description of a knocking noise ... In my experience whenever anyone says "knocking noise" on a car forum it's very each to reach for the "Your big end's gone mate" drama, when we all have a different interpretation of what actually constitutes a knocking noise.

If it's really pronounced then that's the issue and it could be serious. Otherwise it could just be a byproduct of a temporary fault.

So it seems over the last X months you've changed the intake manifold, put a copy of a Weber DGEV on (32/36? and an electronic choke?) and you've tackled the coolant system.

Based on this, my first guesses would be (and again I'm ignoring the "knocking" reference here) that maybe you've developed a leak at the intake manifold, or the servo is faltering (mine went earlier this year and your description above is very similar to what I experienced) or there's something gone wrong with the carb.

One thing you can try is to remove the servo hose from the servo (it runs from the servo to the intake manifold) and block it off with a bolt, then see of the car runs easier. Check your brake fluid level and see if that's dropped significantly too. If you do disconnect your servo hose beware the brakes will probably feel very different!

Have you overtightened the carb and it's started to warp the base allowing air to seep in?

Have you checked the choke to make sure it fully opens and closes as it should?

If it's stuck ajar and can't operate properly it will make starting groggy and will also make running lumpy once worm.

Maybe as a stage 1 you might want to get the car idling without the air filter on and blast carb cleaner into the carb throat, and spray WD40 around the carb base and the intake manifold while its running to to see if that changes the idle revs. Also inspect all the choke and throttle movements and give them a clean too.

Maybe your timing has slipped and you need to get the timing gun on it.

Maybe your vacuum advance pipe has come off, split, or has a little hole in it.

Press on all of your HT leads and king lead. Maybe you haven't reconnected them properly after doing something. Maybe you've got a badly fouled plug and you're running one three cylinders or you have a dirty spark.

Maybe your coil is breaking up.

Maybe you have oil leaking onto the clutch assembly. Does it seem to need much higher revs to make the car get up to speed?

It could be a tonne of things really.

It would be better to assume/hope the knocking is merely a by-product of an engine not running right... unless it's a really dramatic knocking which cannot be ignored.

Thanks so much for this, fella. I consider this a learning opportunity, so will go through all your points tomorrow morning when I go look at the car again - only just managed a 20 minute trip home after seeing your reply.

[ChasR]

Do you have a video? As said, knocking can be a major problem.

[rhymeface]

Jun 11, 2018 7:08:20 GMT ChasR said:

Do you have a video? As said, knocking can be a major problem.

I did try and get one on the road but you can't hear it in the video over the general road and air noise. I might be able to drive round the block slowly and get a friend to do a vid.

I did manage to get this the other day which may well be connected but what I thought was a separate issue,

streamable.com/szogb

This was filmed on a warm day with the car up to temp.

The car has been losing coolant - weirdly, it seems to have stopped now but up to the weekend before last, I was having to fill it up on a weekly basis.

The amount of steamy exhaust that appears varies - that video shows the worst but yesterday on the drive back, sitting at some traffic lights, it was proper billowing and got worse with a bit of black smoke on pulling away.

Just about to go down to the garage now and have a look, so will update further in a bit.

Thanks for all your help so far.

[Deleted]

On a warm day, and a warmed up car... that isn't normal exhaust vapour IMHO.

If that exhaust vapour doesn't smell horrible like burning rabbits then it isn't brake fluid, so it must be your lost coolant. Therefore likely to be a head gasket or the intake manifold.

My knowledge is limited however, so I'm just speculating here. Somebody more cleverer than what I am will correct anything I say that is incorrect.

have you tried pulling off HT leads with the engine running to see if any DON'T change the engine note/rhythm? if you take a HT lead off and it doesn't make any difference to the engine... you're running on three cylinders.

Then there's the usual compression tests you can do on each cylinder which in this case might be worth doing. Check your spark plugs when they are out to see if they are wet.

Check your oil filler for caramel deposits. Have alook at your dipstick and see if it has any bubbles in the oil. Check your coolant for signs of contamination. Might also be worth topping up the coolant up again and running the engine up to temperature with the radiator cap off to see if it rhythmically pukes coolant out of the cap. If it does then that's possibly escaping cylinder compression pumping through to the coolant system.

I suspect the 'knock' might not be devastating and terminal in this case, but you may need a new head gasket.

The only other thing I can think of is dropping some kind of valve cleaner into the oil (Wynn's or similar) in case you have stuck valves that are porting when they should be closed, or not able to close properly. That would require a ruddy good blast around though and you may not want to risk that without a proper diagnosis.

[rhymeface]

OK, the plug in cylinder 4 was wet. Others have a fair bit of corrosion. That along with the steam would be a good indicator of a failed head gasket, right?

I was going to properly inspect the carb as I wondered whether the mounting plates may have warped but at any rate, the intake gaskets probably need replacing (were makeshift rather than proper gaskets). Accelerator cable also needs replacing. So they intake is off.

I popped the rocker cover - oil doesn't look caramel in any way. Looks translucent as oil should (right?). But that needs re-setting.

I needed to drain the coolant prior to intake removal, so that needs refilling.


So, my question is, should I put it back together at this stage and carry out more tests?

[ChasR]

I'd carry out more tests. Compression test would be one way to go but I suspect a leakdown test if you have access to one would be your way forward.

I've had cars kick out that much steam on coldish days when fully up to temperature. It all comes down to how often it's used, the residual condensation in the exhaust (it has to burn off some time from the exhaust; it's one reason why low milers rot exhauts quicker), and the type of exhaust design; IME baffled systems will smoke more.

When I've seen HGs go (and on cars I've owned before) you normally get wisps of smoke coming out, as if the car tailpipe is a heavy breathing chimney!

[rhymeface]

[edited] Just got round to doing a compression test:br]
Cylinder 1: 110psi (100 wet)
Cylinder 2: 128 psi (125 wet)
Cylinder 3: 10 psi (5 wet)
Cylinder 4: 5 psi (5 wet)

There was also a hissing sound during the testing of 3 and 4.

That'll be a new head gasket in order then?

[ChasR]

Hard to say. It runs smooth in your video. I’ve seen cars with Vslve Seat recession but more consistent readings than yours run much worse.

Are the spark plug apertures clean for 3 and 4? A washer stuck down on them maybe?

While it is tempting to call it a HG, i’d check to see the threads and where the spark plug bottoms out in the head is clean; this could be why it was hissing. I’d want a leakdown test to confirm it.

[rhymeface]

Jun 19, 2018 7:49:23 GMT ChasR said:

Hard to say. It runs smooth in your video. I’ve seen cars with Vslve Seat recession but more consistent readings than yours run much worse.

Are the spark plug apertures clean for 3 and 4? A washer stuck down on them maybe?

While it is tempting to call it a HG, i’d check to see the threads and where the spark plug bottoms out in the head is clean; this could be why it was hissing. I’d want a leakdown test to confirm it.

Ah, I should say, that video was from a week or two before the first post here - was running fine.

Spark plug apertures and threads all looked fine but I’ll double check this evening. Cheers for the suggestion.

Want to do the leak down test but haven’t got the tools or compressor to hand.

[rhymeface]

Ok, on the advice of a trusted local mechanic, I went to strip the head off and get on with replacing the gasket, getting the head refurbished and all.

Documenting via Instagram:

http://instagram.com/p/BkTLjvVlpzH

Stripping the engine went easy enough. Revealed a 1cm wide gap between cylinders 3 and 4. Going to check out the pistons and cylinders in the coming days with a view to re-ringing them.

Head is going to a local company to be serviced.