12HT Engine noise after overhauling and its checklist

DiscoTourer
I am interested to know what engine it was which can have it's head on the wrong way around, it is possible on early Victa mowers and some two stroke bikes, makes no difference for them.
At the moment, I do not know of any car engine or diesel engine which can have the head fitted back to front.
Can't imagine any Toyota engine being reversible.
It is possible to learn something new each day they say.

Ross M

Hi Ross,

Just spoke with him....it was the head gasket.....20 years had gone by doh!.

It was an FJ40 1982 4.2litre 2F motor (a petrol one....but I guess you would know that). It was rebuilt, and he drove about 2000kms, before he had head issues....but was a little noisy to start with but the Karratha mechanic told him this was normal.

Broome mechanic realised the issue. It was actually the head gasket was installed up side down causing the oil lines in the head not to match up.

Karratha mechanic copped it on his return and ended up paying the Broome mechanic.

Brett....

I had the same thing head gasket on the wrong way on a 2F which I bought as a rebuilt motor apparently blocks the oil flow I got 400km before it made a noise.

It's not uncommon to be able to fit a lot of head gaskets the wrong way around.
I just bought a fully reconditioned Nissan A14 engine for a mates Bobcat from a young bloke in Sydney.
Mate installed it, started it up, and it ran hot.
Pulled the head and found the head gasket on the wrong way around.
This reconditioning was reputedly done by a qualified mechanic.
Engine rebuilds must be done with exceptional care and attention to detail.

I reckon Derek is on the ball. Engine overhaul should involve checking every specification that the manufacturer supplies for the engine.
Many mechanics don't check specifications on overhaul, they presume every part is O.K.

There not only specifications for piston-to-head clearance, as Derek mentions - there are often specifications for conrod twist, conrod straightness, crankshaft twist, crankshaft runout, flywheel runout - and a dozen other items than can seriously affect performance if not checked upon overhaul.

If you can acquire a mechanics stethoscope, you can often pin down the fairly precise location of a noise in the engine.
Deep noises are usually bottom end - lighter noises such as tapping are usually valve train noises, broken ring, or piston contact with the head.

Once you have defined the area where the noise is, disassembly is on the cards.
The fact that the noise comes in at high RPM certainly seems to indicate the piston touching the head.

Take it to a qualified diesel mechanic

The mechanic was able to fix the oil leak today from oil filter due to faulty seal....

the top noise seems OK and good... its just the bottom tap sound thats getting me worried as dont want to get stranded with family during my offroading trips ..

i have uploaded its sound in one of the post here...

I had first purchased as overhauled engine but it went bust due to faulty fuel pump and even at that time there was this similar tap tap sound from bottom but it was more louder and i think it was the sound of main bearing.

The mechanic changed its main bearing, rings, connecting rods, camshaft bush, camshaft, did oil pump overhaul and lathe machining. Its pistons were fine from the last overhaul

Any ideas what could this be?

Oil pressure needle goes at almost full F on the top on 2000 RPM. On 50 km/hr speed i did notice the main bearing sound diminishing on full acceleration and when i released the pedal the sound was there, however oil pressure remained at full.. whereas on idle it comes down to say around 25%.. my mechanic says if main bearings were loose the oil pressure wouldn't be there.

he thinks its probably the fuel pump injection timing ....

I will also ask him to relook at the installation of piston/con rod assembly incase if he has installed the wrong way round

Tim .. my concern was mainly related to the tak tak sound which can be heard after 40 secs of recording.. and this sound gets more clearer when i release acceleration on 50km/hr (haven't made recording of that as yet)

Whats your gut feel? based on my above feedback and the recording you heard.. do you think its ok?

Tim

I compared it with your recording which i assume was taken while your car was in neutral, whereas mine was taken while it was running on 2nd and 3rd gear over 2000 RPM and i noticed the bottom "tap-tap" sound which can be heard more prominently after 40 seconds on https://soundcloud.com/naveed-ahmed-25/12ht-engine-sound ... i didnt note the bottom tap tap sound in your recording.

i am planning to spend some time with mechanic this saturday and hop he is able to find the source of problem