I understand compression tests are supposed to be done while the engine is warm, but that is impossible for most of the cylinders on my car. I can also compare the results for consistency between cylinders. After testing one and seeing a lot of oil on a couple of the plugs, I'm probably going to pull the engine. It look like a regular engine stand wouldn't work since those mount to the flexplate, right?


Engine stand

I saw this engine cradle that looks like it would work for me to be able to do a compression check with the motor out of the car. I can't tell though if the back mounting points would interfere with the starter. Any insight on this would be great.


Jegs engine cradle

 

I’m going to try and attempt the same thing once my engine is fully assembled.. But the engine stand uses the same bolts the transmission uses.. It does NOT blot to the flexplate..

 

scary shyt

 

The engine stand doesn't attach to the flex-plate, it attaches to the block where the transmission bolts attach.

Good Luck.

 

Do a leakdown test. That will tell you exactly what's going on.

 

What's scary about that? haha Remote switch and power and ground to the starter.

Awesome info, thanks everyone. No need to get a cradle then, I'll just go straight to the stand since I'm not pulling the tranny. I'm going to be doing a leakdown test as well, but it helps to be able to do both.

Thanks!

 

you are going to need a flexplate or FW attached and starter to do a compression test.

Neither stand would work, I have both.

You could "hang" the motor from a engine hoist with that stuff attached....although not something I would do

Just put motor in and do it before you bolt on headers/exhaust manifolds

 

Oh damn, that sucks. Yeah, it will have the flexplate still attached. What keeps it from working with either? Not doubting you, just curious. I'm hoping I can pull the engine and reinstall with the turbo headers on since I have the radiator report removed.

 

I had no trouble doing compression tests, using an engine stand. Put starter on it and crank with a battery / jumper cables. I would never put an engine into a car without doing this test.

I was also able to visit a junkyard, and bring cables/batt/starter, I compressed tested around 8 engines in the yard with no engine stand.

So either way works fine.

Video on the stand attched

These compression tests are important for finding problems before you buy the engine. For example, the bad compression with oil spewing from the cylinder in the first video is a sign of a bad piston/ring (broken ring land probably). I know you are not buying an engine but the example still stands for engines in general.

 

I have doubts the stand will work, the flexplate would come very close to the bolts holding the arms. A cradle will work. I put my engine together on one and was able to bolt up the flywheel, clutch, and starter with no issues.

 

Does the intake manifold need to be on in order to perform the compression test?? I don’t think it does, but my pops said I should put it on.. Suggestions

 

on the engine dolly one the two plates that bolt to rear of engine are on the "inside" of the frame so the flexplate may not clear that square stock frame. You can try. Beyond that there is not enough clearance under the motor on that dolly for the starter...unless you use some wood blocks or something to raise it up the cradle so the starter will bolt to the bottom of the motor

The engine stand with the block bolted on because the 4 ears of that stand "stand off" some (1/2"??) it looks like the flexplate could clear it. You may need to put flexplate on the motor first then bolt it to the engine stand. Typically when assembling the motor on stand the first thing is drop in the crank so you would then need to bolt on the flexplate so the starter would work after assembling the rotating assembly. IDK if you can "slide" the flexplate between engine stand & block and if so can you access the bolts to crank. May have to remove engine from stand (using engine hoist), attach flexplate then bolt the block back to engine stand...assuming flexplate clears stand but in looking at the stand pic it just might. Certainly enough room for starter from under he block

 

Great info, thank you. Since I'm pulling the motor anyways and it's already cold, I'd rather not fight trying to get any more cylinders tested. You meant you tested 8 engines WITH an engine stand, right?

Oh, I didn't realize the cradle was so close to the ground. I'm really hoping I won't have to pull the crank since the motor only has about 500 miles on it. I would think/hope this is more of rings, seals, springs, etc issue. But good info, I'll be prepped for that now! I got my engine hoist in yesterday and have a Happy Hooker on the way to pull her!

 

I'm not quite sure what you're talking about, but here's proof it all fits on my dolly. The bungee cord is just holding up the inspection cover.

 

Your compression issue sounds more like a ring problem so you won't need to remove the crank, just pistons.....unless a broken ring FU a cyl wall then the entire motor needs to come apart and block bore and new larger pistons...or a new block

I have a motor on the stand now and the ears of the mounting tabs on it are over 1" long and I can see a flex plate would not clear the heads on the bolts allowing adjusting of those ears unless I used a few washers between block and stand to stand the motor further away (like 1/4" further) so a flexplate AND the bolts holding it on will clear. It certainly looks doable but you will have to use some washers and possibly longer bolts to secure the motor to stand with flexplate on. Mounting a starter is no issue though

Looks to be very tight bolting on a flexplate though to get to the bolts holding it on with engine on the stand so just leave the flexplate on when you pull the motor and then attach motor to stand. You will see if you need some washers between stand and motor when you go to bolt it on the stand with engine hanging from hoist

 

Spartan

I stand corrected. I have that same stand and your picture clearly shows a FW clears it. Starter mount does still appear to be a problem......but maybe it would clear that lower dolly rail. The "vette" starter is smaller

 

That looks good. Ballsy attaching anything to the steam pipe. I hear that's a beeotch to replace. haha

Isn't that the starter on the bottom right already hooked up?

 

Also, was the stand you used while doing a compression test this type?


Engine stand

 

First apologies for assing up thread with incorrect info

Spartan shows the cradle does allow FW/flexplate mounting. IDK if starter will bolt in but looks like bottom rail of dolly conflicts so ideally Spartan can reply on that. If it does you would be good to go for compression test using it

The engine "stand" pictured looks like mine (Harbor Freight) and those 4 shinny bolt heads (on mine) look like they would make contact with the flexplate unless some washers were used between the ear posts and engine block. No big deal and you would know immediately when bolting motor to it.

The engine stand would easily support the motor with starter installed for a compression test

 

Its possible to do without a stand- so why are people worried about stands? You have to take the engine off the stand to put it into the car anyways. Its not like the stand is part of the engine. test it before you install it, thats all there is to do


If you crank with no intake just be careful not to suck anything up into the engine. This is a fine way to get full compression. The throttle body on the intake restricts air and will reduce compression if not held open, possibly but rare. That example should explain what putting the intake on the head does- and why intakes affect power peaks and so forth. You are tailoring the behavior of air molecules when you place curves or barriers in their path, those patterns can be formed in frequencies are tied with engine performance.