2Gether Insurance 01945 585322

The Mitsubishi Pajero Owners Club®
The Mitsubishi Pajero, Shogun, Montero, Challenger, Raider and EVO 4x4 Owner's Club
 
The POCUK - it's not just a Club, it's a way of life!

 FAQFAQ   SearchSearch   Watched TopicsWatched Topics   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your personal messagesLog in to check your personal messages   Log inLog in 
Click here to link to the Pajero Owners Club UK FaceBook Group!POCUK FaceBook Group  POCUK home pagePOCUK Home  POCUK ForumsPOCUK Forums  CalendarCalendar

Sanity check please - cracked head?


 
Post new topic   Reply to topic    The Mitsubishi Pajero Owners Club® Forum Index -> 4M41 / 3.2 (DiD) models
View previous topic :: View next topic  
Author Message
mjc506
LifeTime Member
LifeTime Member


Age: 36
Zodiac: Virgo
Joined: 28 Jul 2015
Posts: 28
Location: Ceredigion

PostPosted: Sat Mar 30, 2019 16:28    Post subject: Sanity check please - cracked head? Reply with quote

'ning all.

Been chasing a coolant leak recently, which of course eventually lead me towards the engine...

Valve cover off, and pressurizing the rad, and I can see/hear bubbles from where the injector enters the head above no2 cylinder.

To my mind, this means that I have a head gasket leak and/or cracked head in/near cyl no2, AND a leak from the combustion chamber past the injector into the valve cover.

...but, the bubbles still come when intake and/or exhaust valves are open on that cylinder...?

Either way, head off and have a look I suppose?

Thanks,
Matt
Back to top
View user's profile Send personal message
Google
Sponsor







PostPosted: Sat Mar 30, 2019 16:28    Post subject: Google Ads keep the POCUK free to join!


Back to top
SteveW-DID
*****
*****




Joined: 04 Jun 2006
Posts: 826
Location: Dorset

PostPosted: Sat Mar 30, 2019 20:06    Post subject: Reply with quote

I don't think the bubbles by the injector are anything other than a poor seal between the injector and the head. If the injector is tight I would be suspicious that the head has been off before and the 'mechanic' didnt bother with new copper washers on the injector. In the cracked heads I have had, I didn't get rad pressurisation because they tend to crack in the exhaust ports so you get white smoke or slight misfire on startup and slowly disappearing coolant. I would be suspicious that the previous shoddy mechanic that didnt fit new injection washers also didnt torque the head down properly and you have a blown head gasket but definitely dont refit the head without a pressure test. Easy enough to do at home..https://www.youtube.com/watch?v=HNzzBPmmddQ.
To start with I would pull the injector and fit a new washer.
Back to top
View user's profile Send personal message
mjc506
LifeTime Member
LifeTime Member


Age: 36
Zodiac: Virgo
Joined: 28 Jul 2015
Posts: 28
Location: Ceredigion

PostPosted: Sat Mar 30, 2019 22:00    Post subject: Reply with quote

That'd make sense, thanks. Wouldn't hurt to pull all the injectors and replace with new washers while the heads off. Any easy way to tell which thickness head gasket is required/already fitted so I can have it ready? (Mind you, might be better not to trust the previous choice...)

Thanks!
Back to top
View user's profile Send personal message
NDZ
***
***


Age: 49
Zodiac: Taurus
Joined: 29 Dec 2016
Posts: 216
Location: United Kingdom

PostPosted: Sat Mar 30, 2019 22:13    Post subject: Reply with quote

100% respect for that test rig but as for easy? Can't say I've ever had head-sized sections of thick perspex lying around to repurpose but I did find a local engine workshop who tested and skimmed for £60 cash job next day  :wink:

Agree with the advice anyway, worth checking the basics are you seeing any bubbles at the rad cap? Any sign of drips elsewhere once up to temp? Long journeys are best avoided as your coolant loss could quickly become a boil-over and there's still a good chance it only needs a new gasket.
Back to top
View user's profile Send personal message
mjc506
LifeTime Member
LifeTime Member


Age: 36
Zodiac: Virgo
Joined: 28 Jul 2015
Posts: 28
Location: Ceredigion

PostPosted: Sat Mar 30, 2019 23:32    Post subject: Reply with quote

I've actually got some hpde laying around that'd be about the right size, although black rather than transparent is a shame Laughing For that sort of money though, shop time well spent!

It's strange. To start with, I'd notice the coolant level in the expansion bottle dropping slowly over time (once cool), but this has recently accelerated somewhat. It's not overheated, and we keep it topped up.

More recently, I decided to tackle it properly, and drained, flushed and refilled the system. Got all the bubbles out, but the level was still dropping over time. Drained, flushed and refilled again, this time with water only, and also removed the thermostat. Left the rad cap off while warming up from cold. I'm not convinced either way really, there was a little fizzing, but probably just degassing. It did start to bubble when hot, but even then I can't convince myself if that's the crack opening up when warm, or if it could have been localised boiling (rad cap still off)?

Block test came up negative (but I've since read that they're prone to be slow on a diesel, and if the leak is on the inlet side it won't pick up anything anyway), a condom over the rad cap neck doesn't inflate much, but pumping the radiator up to 1bar makes it bubble around that injector, but no other leaks that I can find - the pipes to the rear heater are fine, even the egr cooler checks out ok.

I haven't done a leakdown test, as a can of air spray arrived in its place... I don't imagine it would tell me much more though.

What I can't work out though... were the pressure is coming from to cause bubbles around the injector?! Turning the engine so that exhaust or inlet valves on no2 are open, and even removing the glowplug, there are still bubbles. A crack between coolant and cyl2 would first pressurise the cylinder, and then pass a faulty injector gasket, but opening the valves/removing the glowplug should eliminate any pressure in the cylinder, resulting in no bubbles? And turning the engine to tdc cyl2 should mean high pressure in the cylinder, so bubbles at the injector (but it doesn't seem to)

Is there perhaps a coolant channel nearby the injector socket? Weird place to crack though?
Back to top
View user's profile Send personal message
NDZ
***
***


Age: 49
Zodiac: Taurus
Joined: 29 Dec 2016
Posts: 216
Location: United Kingdom

PostPosted: Sun Mar 31, 2019 8:53    Post subject: Reply with quote

I've got a 4M40 and likewise couldn't really be sure with a bubble test, no drips or fluid contamination yet slow and steady coolant loss then it boiled over towing the trailer. The head gasket was rotten, delaminated and stuck to both surfaces and probably had a dozen routes it could theoretically get rid of coolant!
Back to top
View user's profile Send personal message
mjc506
LifeTime Member
LifeTime Member


Age: 36
Zodiac: Virgo
Joined: 28 Jul 2015
Posts: 28
Location: Ceredigion

PostPosted: Sun Mar 31, 2019 23:38    Post subject: Reply with quote

Any tips where to find replacement copper gaskets for the injectors? I'm having no luck in the usual places, is it a dealer only part?

I also suspect I'll have trouble actually removing the injector - slide hammer type tool should do the job?
Back to top
View user's profile Send personal message
mjc506
LifeTime Member
LifeTime Member


Age: 36
Zodiac: Virgo
Joined: 28 Jul 2015
Posts: 28
Location: Ceredigion

PostPosted: Mon Apr 01, 2019 22:29    Post subject: Reply with quote

Got the injector out. I was expecting it to be more stubborn than it was!

The injector nozzle is a little carbon-y, but not too bad. Of more concern is the oil-water mix on the injector body:

https://photos.app.goo.gl/uZ3Jr8NKSPyoNq8N8

I also note that the o-ring is all cut up. I don't believe I did this removing the injector - more likely it was cut during installation, or perhaps damaged by heat/pressure over time.

The copper gasket looked good. No evidence of combustion gasses passing it.

I also found a crack in the injector socket - pressurising the radiator would result in coolant leaking into the socket: (poor photo, difficult to capture)

https://photos.app.goo.gl/edfMTDzsZ8cGoRnFA

This makes sense to me now - a leak into the combustion chamber should still not bubble up past the injector unless that gasket had (also) failed, which should also show carbon build up under the valve cover. This leak doesn't affect the combustion chamber, and only has to pass that (damaged) o-ring to bubble. The coolant passes through the crankcase breather and gets burnt, and as the system cools after shutdown draws replacement coolant from the header tank. Still seems like a strange place for the head to crack, but I'd have never have known about it if that o-ring had held...

So - how to fix it...

1) Ignore it - £free, but that copper gasket is unlikely to seal again and I'll need to find a fitting o-ring too. We'd just need to keep topping up the header tank
2) Replace the copper gasket and o-ring - this should create a sealed space and the coolant cannot leak far...
3) Replace the copper gasket and o-ring, and 'repair' the crack with epoxy - perhaps slightly ''better' than '2' above, but could result in gluing the injector in (not necessarily a bad thing? I'm unlikely to have to replace either injectors or head in the lifetime of the engine...)
4) New head - £££££

Currently leaning towards 2) above to start, and then perhaps 3) if that fails... any other ideas?

Struggling to find any of those copper gaskets (in the UK at least). A supplier in Aus (but long lead time), and a few in France and Poland, who don't ship to the UK...
Back to top
View user's profile Send personal message
mjc506
LifeTime Member
LifeTime Member


Age: 36
Zodiac: Virgo
Joined: 28 Jul 2015
Posts: 28
Location: Ceredigion

PostPosted: Thu Apr 04, 2019 12:20    Post subject: Reply with quote

Managed to find a supplier for the copper conical gaskets and o-rings - Viamoto, and I should have these Friday...

I've also ordered a new set of nozzles - It looks like the injectors have never been replaced, so it seems like good insurance. I'll pop test them all before and after changing the nozzles and see how things are...

I'm still not sure if it would be better to try to fill the crack with epoxy or not. A 'proper' repair by pinning or welding is not possible here - no access inside the injector socket. I could rough up the surface with emery cloth, apply epoxy, and use an injector body (coated in oil or vaseline) as a mould of sorts, to make sure the epoxy won't affect fitting of the injector. It may not stick particularly well, but pressures and temperatures should be relatively low, and if it fails its no worse than leaving it as is anyway.

On the other hand, I'd have to be careful not to let anything drop down into the combustion chamber, else I'll have to take the head off anyway.

If I apply the epoxy, I can pressure test again to test it (and also to find other cracks I've missed... hopefully not!)

I haven't removed the head - it doesn't appear to have been removed before (no marks on the head bolts, but I guess they may have been replaced) and I don't believe there's anything untoward in the combustion chambers (no hissing/bubbling etc through glowplug holes/inlet/exhaust manifolds during the pressure tests) and the risk of damaging anything or having to wait for a new head gasket isn't worth it at present. Of course, should another leak become apparent after repairing the above, I'll have to remove it anyway, but my other half needs the car for work...
Back to top
View user's profile Send personal message
mjc506
LifeTime Member
LifeTime Member


Age: 36
Zodiac: Virgo
Joined: 28 Jul 2015
Posts: 28
Location: Ceredigion

PostPosted: Thu Apr 04, 2019 18:36    Post subject: Reply with quote

Interesting... just pulled the other three injectors.

All have cut/ruined o-rings, and each injector cup was full of engine oil.

The nozzles on these three injectors were not carboned.

I suspect that the torn o-rings allowed gas to be expelled as the engine warmed up, and allowed the oil to be sucked in during cool-down. No oil was on the injector nozzles (until it started dripping down).

Injector number two had coolant entering that space, so the oil didn't get sucked in there nearly as much.(?) Perhaps this also cooled the nozzle, leading to the increased carbon build up.
Back to top
View user's profile Send personal message
mjc506
LifeTime Member
LifeTime Member


Age: 36
Zodiac: Virgo
Joined: 28 Jul 2015
Posts: 28
Location: Ceredigion

PostPosted: Fri Apr 05, 2019 21:54    Post subject: Reply with quote

I shall count today as a success!

Wiped the excess oil off the injectors, and put them on the nozzle tester:

Code:

Cylinder:         1     2     3     4
Opening pressure: 16.5  17.0  17.0  16.5 (MPa)


Spec is 17.60 to 18.58, although I could only really measure to the nearest 0.5 MPa on my gauge. Not great, anyway. Each nozzle also started to drip when held 2 MPa under opening pressure, slightly below 10secs. The spray pattern was also not so good, with two or three out of the five jets dribbly and weak. They did, however, appear to be the original nozzles, so perhaps not too bad for 260k miles.

I disassembled, cleaned, inspected and rebuilt each injector with new nozzles. I suspect the existing ones could have been cleaned reasonably well, but this may not have fixed the opening pressure and drips. Besides, new nozzles were cheaper than cleaning...

After the injectors had been reassembled, they went back on the tester:

Code:

Cylinder:         1     2     3     4
Opening pressure: 18.0  18.0  18.0  18.0 (MPa)


Much better! Spray pattern was (of course) good, and they did not drip or dribble when held just beneath their opening pressure. Happy with that Very Happy

The new copper gaskets and o-rings also arrived today as promised - many thanks to Mike at Viamoto. I decided to try epoxy on the crack in the no 2 injector cup, so applied this, then fitted each injector (with the new copper gasket and o-ring, and with a light coating of oil to prevent the epoxy sticking), and torqued up.

While the coolant system was empty, the epoxy not yet set, and the EGR pipe was not yet fitted, I was concious that the injectors had air in them so wanted to get them primed to stop them sticking (and, to be honest, really wanted to hear it run to prove I hadn't broken something else!) The engine cranked for quite a while before the first injector started to fire, but was then quickly up and running on all four cylinders Very Happy Some good proper smoke out of the EGR cooler as well Laughing I shut it down quickly, and removed the valve cover to confirm that there were no signs of diesel leaking. Nothing yet, but it'll need to run longer than that to be sure.

Tomorrow I've got to replace the rear section of the exhaust (unrelated, but convenient timing I suppose...), refill the coolant system, pressure test, and give it a run!
Back to top
View user's profile Send personal message
mjc506
LifeTime Member
LifeTime Member


Age: 36
Zodiac: Virgo
Joined: 28 Jul 2015
Posts: 28
Location: Ceredigion

PostPosted: Sun Apr 07, 2019 18:05    Post subject: Reply with quote

Well, exhaust replaced, coolant system filled and bled...

It runs, no leaks*, and the coolant system holds pressure Very Happy

Idle is much better than before, especially when held on the brakes while in drive or reverse - before, there would be slight vibrations and the revs would rise and fall slightly when warm, but this is now gone, and revs are stable at ~600rpm.

Will keep an eye on fluids and levels for a bit, but I think it's sorted Very Happy




*I think I have a slight exhaust leak - I sheared one of the bolts on the flange on the exhaust header for the first EGR pipe. It doesn't appear to leak at idle, but not sure about higher revs. I have a clamp around it now which appears to be working but I'll fix it properly next time its off.
Back to top
View user's profile Send personal message
NDZ
***
***


Age: 49
Zodiac: Taurus
Joined: 29 Dec 2016
Posts: 216
Location: United Kingdom

PostPosted: Sun Apr 07, 2019 20:41    Post subject: Reply with quote

Can't criticise the detail and amount of work you're putting in here! Did the head ever come off at any point?
Back to top
View user's profile Send personal message
mjc506
LifeTime Member
LifeTime Member


Age: 36
Zodiac: Virgo
Joined: 28 Jul 2015
Posts: 28
Location: Ceredigion

PostPosted: Sun Apr 07, 2019 20:54    Post subject: Reply with quote

Nah, just stumbling from one idea to the next haha

I didn't take the head off. It would have been 'better' to have it off and pressure treated, but I didn't have the time to do so (my other half needs it most nights for work) and the additional risk of something going wrong whilst doing so didn't seem worth it. It was definitely cracked in the injector cup, and I couldn't detect any leak in the combustion chambers through the headers, combined with the lack of traditional symptoms.

Of course, should the loss of coolant continue, a leak down test would be sensible, which may then result in the head coming off... Nothing done so far, however, will be affected by that if it comes to it (I hope!)
Back to top
View user's profile Send personal message
Display posts from previous:   
Post new topic   Reply to topic    The Mitsubishi Pajero Owners Club® Forum Index -> 4M41 / 3.2 (DiD) models All times are GMT + 1 Hour
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You cannot download files in this forum


All contents © Hobson's Choice IT Solutions Ltd 1997 on
Powered by phpBB © 2001, 2002 phpBB Group