4a problem, maybe Broken/damaged valves???????

[maxhag]

hey guys,

I just thought i would get some opinons before i rip the engine apart or toss it out altogether..

My question is:

What would be the symptoms of broken/damaged valves in a 4A?



The story:
I was driving my 4a (in good cond, 280,000km, reg serviced) to work and i was just driving granny style (60kph) when suddenly lost engine power and it began to 'rattle' when i was to rev it. I pulled over..


After limping the car home, and inspecting the engine, this is what i have noticed.......

1. Only running on 2 cyl (cyl 1 and 2 NOT WORKING)
2. Spark to all plugs is ok
3. No engine rattle on idle or slow gradual revving BUT rattles when you give it a sudden rev.
4. Engine DOES NOT blow any smoke (fuel or oil) but exhaust smells very 'fumey'
5. Headgasket???? Water is perfect, no sludge etc..... Oil looks fine........
6. Idles smoothly (for only running on 2 cyl)

Any ideas?

I was thinking the valves but i havent delt with damaged ones before.............


thanks

J Riftin

[ke70dave]

prolly good idea to do a compression test before ripping it all appart, also check if theres any bubbles in radiator

also are you getting any blow-by out of the top of your crank cover, if your valves are buggered youll be getting alot of air out of there

[gunbz-r]

rocker assembly, most probably. pull your rocker cover off and have a look, a bent, stretched or brocken valve would do more then a rattle whil revving, i would think anyway.

pull the rocker cover off and have a look.

[slydar]

could also be broken crank. early 4ages do break crank shafts.

pairing of 1 and 2 kinda suggests this.

these engines have also been known to remain driveable with broken crank shafts.

sounds odd. sounds kinda bad though. luckily wrecker engines are not too expensive.

[slydar]

<div class='quotetop'>QUOTE (gunbz-r @ Dec 30 2007, 02:54 PM) </div>there are no "rockers" in any 4age engines.

gunbz-r. you would be better off reading a little more and posting a little less.

[maxhag]

yeah, i did pull the cam cover off and checked springs etc...... all looks fine......

I was also thinking the same thing with the Crankshaft, but i thought it couldn't possibly run like that....


No bubbles in water...

[slide86]

comp test would be the best thing for this.

my daily had the same problem. turns out the head gasket blew between cyl 1 & 2. causing the compression to jump between cylinders . it was also only running on 3 & 4 cause of it.

i say comp test it and it should give you an indication as to whats going on in there

[maxhag]

will do this arvo....

I thought there would be other signs of the headgasket blowing ......

thanks guys.

Can someone also tell me the touque settings for the head when i put it back on....

Adios amigo's


J Riftin

[4A-GE Power]

If you had a broken or cracked valve the engine would still run but it definitely would not have dropped two cylinders completely unless a number of valves had gone. I'd say slide86 is on the right track with the headgasket. I believe 4AGE's do have a head gasket problem like 7M's do. Worse case the crank is gone but it would have had to be hammered for it to break coz they are pretty strong. torque specs as per Toyota 4age manual: torque all bolts to 22ft-lb in a criss cross pattern. then tighten a further 90 degrees and another 90 after that.

[maxhag]

its a 4a (SOHC) Not 4age. do they run the same cranks?