A noise from underneath

[sam79]

Sorry to be off topic again.

I'm still helping my brother in finding a decent Chevy Van and we have found a real nice one today. There's just one thing that is a bit of a worry for us.

When we took it for a test-drive we heart a banging noise from underneath when taking a hard right turn. The owner thought it was the mounting-rubber that was at the end of its life and therefore the transmission was banging against the support. Could this be the problem or should I think of something else that causes the banging noise, such as a bad tranny.
The van was equipped with a 305 engine with a TH400 transmission. The thing I thought about is that this Van came with a TH350 and they have changed it to a TH400 without swapping the drive-axle. So I thought the drive-axle could cause the banging noise because it's not the correct length.
I'm a completely ridiculous thinking this could be the problem. If so, please say so!

Any help in this matter would be very appreciated by me en even more by my young brother.

[Russell]

Might be the shocks... Grab them and see if they wiggle. If they do, then they are just clanging whenever you take that corner.

[sam79]

Russel,

Thanks for the suggestion. I will take a closer look at the shocks next time we are going over there. I hope that will be the problem since that is easy to repair.
I just hope that it is not a bad tranny, anything else I can fix but a transmission is way out of my league.
Just keep giving my suggestions so I can check them al and feel more secure about buying the Van. This way my brother will feel more secure on it to, he is totally depending on my opinion.

Thanks you all.

[Russell]

Hey Sam -- I know a 15 year old guy who rebuild a TH400 Turbo in my mechanics class with poor tools last year and installed it in his truck. Its totally not outta your leauge if you have the proper documentation and diagrams for it. I doubt it is the transmission as it is happening upon taking a corner, that sounds a lot like a shock, or possibly a swaybar / control arm or something thats loose. Just crawl under the front end and look for broken bolts, loose components, or anything that looks like it is bent, or otherwise physically damaged. Being in the Netherlands, I'm sure parts arn't nearly as easy to come by as they are in the US, or in my case Canada, make sure you're buying a solid truck Transmission will be going if it slips outta gears, or shifts real hard or shifts at odd times (and adjusting the little vac control valve doesn't help)

The transmission shouldn't be swaying at all, it should be bolted directly to a crossmember that is bolted to the frame. Also make sure you check the rear end, make sure it doesn't clunk when you shift like my truck does, that indicates some wear...

I mean, I'm not an expert by any means, but it should be fairly simple to tell if something is wrong

[Blue Beard]

Best bet if in doubt is take it to a local mechanic and spend a few $ for an instection.............save a lot of headaches and worries, and maybe a bad investment....

[C-10volvo]

Originally posted by Blue Beard
Best bet if in doubt is take it to a local mechanic and spend a few $ for an instection.............save a lot of headaches and worries, and maybe a bad investment....

YES!
Take it to get it checked out! my friend forgot that minor detail when he picked up his blazer. He was having trouble with it cutting out when it was cold, so I took a look at the vacuum lines. I ended up telling him that he has a cracked frame (in two places), 305 c.i. motor (seller said it was a rebuilt 350), leaking output shafts, two sparkplug boots not connected and 4 vacuum lines not connected.

Anyone want to buy a blazer?