Suspected problem with head gasket

[Cadiz]

Hi peeps. I'm having trouble with my 'R at the moment. It all started a few days ago when it started misfiring while driving down the motorway - at first it only missed when I applied throttle - it was ok at a steady 3500 revs. The miss firing has got steadily worse since and last time I fired the car up there was a lot of moisture coming out of the exhaust so I am suspicious that the head has gone. Does this sound right to you?? Is there anything I can check to confirm this without taking the top off the engine??

(P.S I'm not very mechanically minded so please be gentle!! )

 

[mattygti-r]

compression test?

 

[Anonymous]

Take it to Nissan and they will do a chemical sniffer test on the engine coolant. If there is any exhaust gas present the bluey green liquid turns red.

Speak to one of their service guys in the work shop before you book it in, because they'll probably do it for free on the spot. All they need to do is remove the rad cap.

While you wait to do that you can check for sludge under the oil filler cap, and also check the engine oil for any signs of it getting a pale / milky look to it. Your symptoms describe a fail head gasket though.

Did you know that the most common cause for head gasket failure is detonation? When having it replaced check the piston crowns for signs of pitting.

 

[Toady]

Take it to Nissan and they will do a chemical sniffer test on the engine coolant. If there is any exhaust gas present the bluey green liquid turns red.

Speak to one of their service guys in the work shop before you book it in, because they'll probably do it for free on the spot. All they need to do is remove the rad cap.

While you wait to do that you can check for sludge under the oil filler cap, and also check the engine oil for any signs of it getting a pale / milky look to it. Your symptoms describe a fail head gasket though.

Did you know that the most common cause for head gasket failure is detonation? When having it replaced check the piston crowns for signs of pitting.

my testing fluid is blue and goes green for petrols yellow for diesels. its a snap-on item too.
Cadiz - where abouts are you from mate? ill do the test for you if you want? it could also be that your plugs are knackered? tho that wouldnt explain the mist. try them 1st as theyre only cheap, but if your near oxford way, send me a pm and ill do a leak test for u!

 

[Cadiz]

Thanks for the info guys!!

Yesterday I ran a compression test with some interseting results. Here's what happened...

1. Removed all spark plugs and discovered 2 - 3 inches worth of water in plug hole #2.
2. After removing the water from #2 I ran a compression test on all four cylinders with the following results:

#1 = 154 PSI
#2 = 160 PSI
#3 = 157 PSI
#4 = 160 PSI

(Note: the engine had cooled down a little inbetween idling and actually running the test. This may account for lower pressures.)

This I did not expect - for a head gasket fault I would have thought constant pressures across all cylinders would be a sign that the gasket was ok. Maybe its water in the petrol!?!?! According to the chart on the back of the testing kit all the pressures were well within the green - anything up to a 15 PSI difference is ok.

After the test I changed the plugs and let the car idle for a good 10 minutes. During this time the engine ran silky smooth with no signs of backfiring. I then applied some throttle and it seemed to run smooth at 3 - 4000 rpms.

Feeling confident I took the car out for a quick spin. After only getting about 200 yards down the road the missfiring began again - so I limped back home.

At the moment I am struggling to figure out what the problem is. I still suspect head gasket as I cannot explain why there was water in plug #2 and that plumes of moisture had been seen coming out of the exhaust. The oil in the sump looks ok and there's no crap under the filler cap. The only thing I can think to do next is change the rest of the ignition system (dizzy, rotor, leads) too see if it's an electrical fault.

 

[Uncle Winnet]

dont think it the head gasket i would put a new set of leads on and a new dizze cap on to if it was head gasket 1 of the cylinders would be well down but they are all with a few psi of each othere



john

 

[Fast Guy]

1. Removed all spark plugs and discovered 2 - 3 inches worth of water in plug hole #2.
2. After removing the water from #2 I ran a compression test on all four cylinders with the following results:

Your compression's OK.

Water in the plug well commonly gives similar problems to what you have. It maybe worth putting the plugs and leads inside to dry out overnight or even putting some new ones on to see if that cures it. The could still be very moist inside :shock:

 

[Cadiz]

Thanks for the replies!!

I'll get a dizzy cap, rotor & a set of HT leads ordered tomorrow and post back the results once I've fitted 'em.

 

[daz]

may aswell do the coil aswell but get a nissan one as there are quite a few types. i ordered one for mine from a local motor factors and i think that they sent me one for a 1.3!!!!!!!!!!!!!!!!!!! may be expensive but cutting corners with these cars results in more problems..

 

[daz]

out of intrest what boost are you running... as could be a problem with the gapping on the plugs daft as it sounds. but i did have a similar problem with mine and replaced plugs, coil, leads, dizzy cap and rotor arm.

 

[Cadiz]

daz, it's running standard boost. When I changed the plugs over I gapped them at 0.8 - although I'm not 100% sure this is correct. :? I searched the forum for the correct gappage and everyone seems to have a different opinion as to the right amount. My old plugs were pre-gapped to 0.8 (HKS Iridium). The new plugs are NGK PFR7B.

 

[Fast Guy]

When I changed the plugs over I gapped them at 0.8 -

The manual states the plugs are NGK PFR7B-9, which means they come pre gapped at 0.9mm It says they don't need checking or regapping between replacements :shock: and doesn't specify a gap, so it must mean they are gapped to 0.9mm as standard. I think people normally goto 0.8ish when they start upping the boost. It may run ok on 0.8mm, I wouldn't like to say having no experience of trying it.

 

[Cadiz]

Thanks Fast Guy - I'll make sure I regap to 0.9 while I've got the IC off replacing the other bits.

 

[Cadiz]

Well, I finally got round to fitting the new leads, dizzy cap and rotor arm today and so far I've not had any misfiring whatsoever. Looks like the head gasket is ok after all. The car is running nice and smooth!!

Thanks for the help guys!!