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r3l4x

hi. i have a 1996 6n 1.0ltr that is burning oil and i tinking of swaping it with a 1.3ltr from a 1995 6n. 

are the engine interchangeable as the 1.3 is carb and the 1.0 is mpi? 

 

im talking in swaping only the block and head from a 1.3 and kepping the intake manifold of the 1.0 

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my guess is that timing belt broke and cylinder head was replaced. ive never seen a cylinder head valve damage but i assume it would have visible damage not just on the valves.   ive order a

dvderlm

1995 ?

 

Sorry, it's Single Point Injection (SPI) not carb.

 

SPI - Bosch Mono-Motronic  MA1.2 or MA1.2.3 according to

 

https://www.ultimatespecs.com/car-specs/Volkswagen/3026/Volkswagen-Polo-3-6N-10.html

 

https://www.ultimatespecs.com/car-specs/Volkswagen/3025/Volkswagen-Polo-3-6N-13.html

 

ADX engine has 30% higher air flow from 1296cc than 1043cc AEV.

It'll run, but there may be some flat spots if the ECU fuel map is very different and that's beyond my knowledge.

 

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r3l4x

its SPI but in Portugual we usualy call it SPI carb and a MPI we call it injection.

 

my concern is not knowing if the 1.0 ecu will work with the 1.3. 

 

looking at both engines the parts seen to be interchangable. 

 

also is there a way to tell if piston rings are bad or if is valve or head gasket? 

the 1.0 as blue smoke when accelerating. in idle doesent smoke but smells at oil. 

it also had some grey gunk only in the coolant reservoir. 

 

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dvderlm

I see. I don't know enough about any ECU differences.  

 

A compression test will tell you whether the piston rings are worn or the valves are worn, by whether there's a change in reading when you add oil for wet test after dry test.

 

https://www.freeasestudyguides.com/compression-test-injecting-oil.html

 

You can check for CO2 in the coolant using a combustion leak detector, which has a fluid chemical that will change colour typically from blue to yellow/green if there's a head-gasket fault.

 

Are there any OBD fault codes? 

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dvderlm

The ECUs are different part numbers so not the same.

 

I reckon

  • ADX ecu is 030906026AP or AJ
  • AEV ecu is 030906026BX or AK or AM

Fit a second hand ECU from ADX?  

It might need key coding by a Volkswagen dealer for a significant fee.

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r3l4x
Posted (edited)

i bought a compression tester and tested with engine cold and hot at about 75°C. 

 

from timing belt to dizzy:

cold:

105   110    100   105

hot:

95     100    95    100

 

with full throttle

130   125    125    125

 

the tester only counts in 5 psi so the values are rounded to the higher. 

 

also the engine does a knocking sound that apears to be coming from the middle of the cylinder head

 

the only OBD code it shows is lambla. 

 

some background on what im doing:

i have a 1995 1.3 SPI polo that as a good engine but body/interior is crap

 

and i last week bought a 1997 1.0 MPI polo that was supposed to running only in 3 cylinders wich is not the case. the engine was only misfiring hard. 

ive drove the car home about 35 miles and above 3000 rpm it run good no noticeble missfires no smoke all the way in any rpm.

when i got home started to check the engine the dizzy was realy bad doesent have a thermostat and there was grey gunk in the coolant reservoir. 

so i cleaned the reservoir and removed the fluorescent green coolant added tap water and swaped the dizzy cap with the 1.3. after that it started smoking blue but stopped missfiring

Edited by r3l4x
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dvderlm

There's not much variation between cylinders which is good.

Hot will be less than cold, so okay.

But, 105psi is just over 7 bar which is the wear limit of rings/bore.

You need to do a wet test and see if you get higher readings.

 

Running without thermostat will be cooler engine that might fuel richer as though winter weather running, but that would show as black sooty exhaust. Any idea why no thermostat was fitted, they are cheap?

 

Blue smoke is oil. If not worn piston rings, 

maybe valve stem seals or valve guides or overfull?

 

Also, just water as coolant is okay for short period to test in warm Portugal (not good where it can freeze) but antifreeze/coolant also has rust inhibitor.

 

You could try swapping the ECU to see if it works, and also check whether the cable plug is different. First check with a voltmeter that the same pins carry 12v, just in case the wiring changed!

 

Edited by dvderlm
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dvderlm

lambla -

 

Once thermostat replaced (after coolant system flush). 

Find and mend lambda wiring or replace the lambda sensor otherwise fuel trim will be probably be limp-mode.

 

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r3l4x

i dont think swaping ecu will work as one is SPI and the other MPI. i was thinking on swaping engines if the 1.0 cant / not worth be fixed. 

tap water is just until i know wath to do with the engine. 

 

just call the seller and this is what he old me:

the car was bought about a year ago and was running bad and a mechanic told the previous owner that it was only running in 3 cylinders and was better/cheaper to swap engines and after that the car hasn t run. only about 2 months ago when he put it for sale he added about 3 liters of coolant as the car was empty. 

 

the 105 value was with out pressing the throttle. with full throttle was

130 125 125 125. 

 

tommorow i will do a wet test if the test is good is there anyting else i shoud do before removing the cylinder head? 

 

also could this be a possibility?

the car was without coolant maybe the head gasket just got rusted and after adding collant plus a 35 miles on high revs it just blew up. 

 

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steveo3002

the compression tests sound okay...doesnt sound like the head gasket 

 

still if its unknown history might as easy to throw a known good engine in it

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r3l4x

so no luck finding an engine localy with warranty so in the meantime i just pulled the head off to see whats inside. 

 

spacer.png

 

spacer.png

 

IMG-20210506-202531.jpg

 

IMG-20210506-202536.jpg

 

i dont know if the black silicone is part of the head gasket or not but its 2 layer metal gasket with about 0.6mm thickness.

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dvderlm

Gasket is 0.6mm now. Probably started life as 0.9mm.

 

Is that orange rust on the piston crown?

That surely means water has entered the combustion chamber.

Maybe stored in damp with no sparkplug?

Or coolant had some crappy miracle additive added to reduce / stop leak and it blocked the thermostat too (guess).

 

Scrape the old gasket off the head and check whether it is warped ( a steel ruler edge and a torch?)

(or engineers' blue ink and plate glass)

 

If not warped you could get it skimmed. Are valve faces and seats in good condition?

 

 

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r3l4x

tomorrow im gonna clean it. i was looking at the photos and just realized that it looks to be valve marks in the pistons or are they like that? 

 

dont know if it rust or not but doesent come off scrubing with fingers but the head in that piston also has different color from the others. 

 

looking at the block im pretty sure i know what coolant the previous owner used as i used one that had the same color and was very corrosive on ruber and alluminium.

 

removing the thermostat is kinda of a common practice in Portugal because most people dont want to spend 5 or 10 € on a new one just because the car still runs "fine" without one

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steveo3002

at one time some coolant were unable to mix with others , it turned to gel , never seen it myself but maybe suggests that happened , radiator and heater matrix probably ruined too  

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r3l4x

yep heater matrix is also leaking. the radiator its not leaking. i just find weird why it only started burning oil after i replaced the coolant with tap water and messed with the dizzy. with the head off is it possible to check for leak in the valves?  im thinking valve seals went bad after driving the car home

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dvderlm

Yes, that looks like piston/valve contact, not valve cutouts.

 

One or more valves may be bent. Are they seated well in their holes if you remove camshaft?

 

Get a valve spring compressor tool, squash the spring around a valve, release the collet (two halves of a cone) and take a valve out. Put it in a drill chuck and spin it. You'll see if it is bent.

 

Replace collet halves using grease or small magnet when reassemble.

 

The seals are around valve shaft. A new cylinder head gasket kit should have new seals. When worn you get blue smoke on deceleration, or when setting off after sat idling.

 

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r3l4x

already took the valves out and they are not bent. those marks dont seem to be to recent.  checked the block and head with ruler and a 0.05mm feeler gauge dont appear to be warped. 

tried to remove the valve seals with needle nose pliers but they just fall apart and they dont feel like ruber they are hard and brittle. 

also in the process of removing one seal a messed up the tip of a guide. 

are the easy to replace? 

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dvderlm

Good news about the valves. So old damage and maybe gasket already replaced once, perhaps. Maybe only contact at starter motor speed?

 

If stem seals were hard, they would not seal well as valve slides and rotates.

The tiny inner spring that assists the seal as expands would have no effect.

 

Guides need heat to expand the block to remove and fit.

I've not done it, but I have paid a machine shop to do so (and ream guides for bigger stems and reface).

 

What about the mating surface of valves? Any pitting or cracks?

 

You can lap the valves back in to get good seal using fine paste and a drill holding the valve stem with care. A torch will show any gap.

With new valves a suction cup twisty stick can be used on the piston face of the valve.

 

 

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r3l4x

my guess is that timing belt broke and cylinder head was replaced. ive never seen a cylinder head valve damage but i assume it would have visible damage not just on the valves.

 

ive order a head gasket and valve seals and when they arrive ill take the head to a machine shop 

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