Head Gasket. . . or is it?

[JDMicra]

Hi all just joined the MSC so still a newbie.

2 days ago I bought a K11 Micra super s with 127000 on the clock. Bodywork is still in great shape, and it has had a respray very recently (I live in Malta, so rust isn't really an issue).
I got home and opened the rad cap.... EMPTY. I filled her up and bled the system. I've been keeping a close eye on the radiator fluid as I was afraid I might have blown the head gasket.

Here is the funny part...
When I start from cold I get a few bubbles the size of a pin head, then after about 4/5 secondsit stops. Coolant flows well, no bubbles, no white deposits in coolant, no change in fluid level when I rev. Oil is clean and sparkplugs also seem decent. Car pulls well and no white smoke from the exhaust. I have noticed a tiny leak on one of the hose pipes that goes into what i'm assuming is the water pump, near the engine block. When I start from warm I get no bubbles whatsoever.

Any ideas as to what may be causing this? Thanks!

 

[frank]

the pump is behind the belts JD, best to just fix the leak and then see how it fares

 

[pollyp]

maybe a leaking o-ring where the coolant return pipe is inserted into the waterpump inlet behind the engine block.
look underneath with bright lighting and look/feel for any dampness around where the join is.

that seal can only be disturbed for a short number of heat cycles or period from new. over time the rubber would've hardened n cured into the shape of the sealing faces and if its ever been disturbed beyond that time it tends to fail n leak slowly
but whenever anyone disturbs that return pipe o-ring it's always advisable to replace the ring

 

[JDMicra]

Thanks for fast replies. There are no obvious leaks around the water pump, the leak I've seen is at the front of the engine block, right under the distributor. There is also some corrosion around it so I guess its been leaking for a while, maybe explaining how I got the car with very little fluid in her. Could this explain the bubbles in the rad?

I've also noticed something else, when the bubbles start idle drops slightly. It lasts maybe 5-10 seconds max then I get no bubbles and the car just warms up normally. The warmer she gets the smoother she runs.

Quite confused at this stage to be honest, I keep thinking its the head gasket :/, which would be a major blow as I've already paid quite a bit for the car. . . (1 of only 3 Super S in Malta so considered a bit of a rarity)

I'm taking the car to a garage meanwhile to get an expert opinion, feel free to throw any other ideas at me in the meantime

 

[Stani1029]

I doubt its the headgasket, there are 4 coolant pipe ends underneath the distributor so it could be any of those. Surely if theres a leak then the water is being replaced with air hence the bubbles?

 

[JDMicra]

Taking them apart this weekend, will post about what turns out

 

[flipside]

you could do a leak down test ,if you get bubble's at the rad pressure cap it's a head gasket. did you check the oil filler cap for mayo? also is the water pump bearing noisey?

 

[JDMicra]

Im disassembling the 4 pipes mentioned at the mo. Ye bubbles are coming out from the rad pressure cap but at this point I dont think its the head gasket. Temp still fine, oil is clean and holds its level, no mayo whatsoever. My mechanic came up with a theory which I think makes sense. He recons whats happening is when the cooling system de pressurises when the car is turned off, it creates a vacuum, sucking a couple of air bubbles in from the leakey hose. When you start up, those bubbles make their way out of the cap, explaining why its only a few bubbles and only on startup from cold.

I thing its logical enough let me know what you guys think

 

[frank]

the cap has a little one-way valve that allows the coolant to return from the overflow bottle as it cools down JD, but it still could ingest air like you say eh

 

[pollyp]

i tend to find that where the top rad hose connects to the thermostat cover tends to leak if the metal pipe isn't sanded/polished smooth with emery cloth

 

[JDMicra]

Solved this one all

Turns out it was the water jacket on the front of the engine, where the heater hoses connects to the rad top hose.

The metal water jacket itself had failed, complete with a nice big hole in the side, I was actually surprised she held any water at all. Got my hands on a second hand unit from a breakers yard (for free ), cleaned it up, re-sealed it and stuck it on. Decided to replace the heater hoses as well as they seemed a bit perished. Couldn't find the original Nissan ones, but here's a TOP TIP: Suzuki/Maruti 800 hoses are exactly the same diameter, have similar curves, fit on just fine, and cost me just 28Eur.