seized cam 94 mx3 1.8 v6

[tracker]

Some time back I posted regarding a 94 mx3 that I'd bought with a no-run situation-the distributor wasn't turning. I thought it might be a broken belt but when I looked closer, the rear cam is seized. The question is: how big a problem is this? Thanks in advance for all help.

[wytbishop]

Depends why it's not turning. Is anything else turning? I find it hard to believe that a camshaft could stop the engine from spinning.

Let's assume that it is seized. It would likely be due to a serious amount of corrosion between one or more journal and it's cap. Inwhich case you would almost certainly have to replace that head...cuz you're not going to fix that amount of corrosion without machning and welding and more machining. Replacement would be much easier and cheaper.

I think though...that it's more likely that the engine is turning and either the cam is broken or the timing belt is broken and that's why the disty is not turning.

[tracker]

Thanks for the reply. The car was apparently cruising down the street when it quit. I checked the belt and it was broken, but when I got round to checking further, the rear cam is seized for whatever reason, and before I get into pulling the plenum etc I am looking to find if anyone else has run into this and how ugly trying to fix it might be, or if I should just sell it for parts-the car has 177k/km (102,000 miles) and seems to be in good shape overall.

[wytbishop]

Even though it's a non-interference engine, the intake and exhaust valves would still probably make contact if say, you tried to turn one camshaft individually. For example, if you went to turn the rear exhaust camshaft, one of the rear intake valves is always int he open position. Turning the exhaust cam the adjacent exhaust valve would probably hit the open intake valve and it would seem like the shaft was seized.

I don't think it's likely that one of the camshafts is seized on an engine that was working up till the timing belt broke. I could be wrong, but I would not think about scrapping a car with 177k on it because I didn't want to take the intake manifold off.

[marcdh]

I'd consider this a golden opportunity to put a 2.5 in. However I had a cam snap and my engine still ran, I have since replaced the cams and it is running great. So the engine may be easily salvageable but ultimately the only way you'll know is if you open it up!

[tracker]

Thanks to both of you for the info. Sounds like its worth getting dirty for.

[tracker]

BTW-what is the best way to check if it is the exhaust cam ? Pull the cam cover? Try to turn the cam the other way?

[SpatialTerror]

yes i would defantly just drop in a 2.5
i did it in mine about 3 ro 4 months ago.
and it still puts a smile on my face when i press on the gas

[wytbishop]

Have a look at the manual to be sure you understand how the cams work. I don't know how well versed you are so I'm just saying. Basically the camshafts on each bank are connected by the gears which are under the cover. When the timing belt pulley turns one of the shafts they both turn together. So if it won't turn forward at all something might be broke in the head. Try turning it backward and see what happens. If it won't turn forward at all chances are it won't turn back either...but it might move a little.

I would pull the Intake and the rear cover and have a look. If something's broken it will be pretty obviously most likely.

[tracker]

Thanks again....I ought to know real soon.