High compression

[losh1971]

Hmmmm, wondering if I should see if I can get my engine leak down tested before I pull the heads off? I was going to comp test prior to heads coming off and then again after, just to compare and see how much improvement fresh heads and 10 thou shave gives to the comp. Not sure what to do now?

 

[shane_3800]

Because you can tell whether cranking pressure is relatively normal, but you can’t trace where the lost pressure is going. It won’t tell you if you have a small head gasket leak, for example.

A leakdown test allows you to assess how well the system can hold pressure in a controlled setting (not influenced by throttle openings, temp etc.

Things you can easily find with a leakdown test:
-Headgasket leaks - bubbles in coolant (easy to see due to no coolant disturbance due to normal coolant flow when running), pressure leaks into adjacent cylinders can be heard also.

-Intake/exhaust valve leaks - listen through intake or exhaust for airflow.

-leaking into crankcase - listen for airflow through filler cap.

A compression test is better for assessing the condition of a good running condition, or using in combination with a leakdown test. If you had to purchase a leakdown tester OR a compression tester, it would be leakdown tester for sure for diagnostic purposes.

You can test for all that with a compression tester and a teekay tester. If the engine has low compression on one cylinder it's going to be head off any way. We just send them to the engine shop and they pressure bench test the head the vac test the ports.

In the 12 years I've been in the trade I only had one **** up where we quoted a head gasket and we did the job and it turned out the block was cracked.
It was a ford territory and we did a second hand engine for they guy and only charged him for the second hand engine.
Or the engine shop never pressure tested the head..... They said they did though.

 

[EYY]

You can test for all that with a compression tester and a teekay tester. If the engine has low compression on one cylinder it's going to be head off any way. We just send them to the engine shop and they pressure bench test the head the vac test the ports.

In the 12 years I've been in the trade I only had one **** up where we quoted a head gasket and we did the job and it turned out the block was cracked.
It was a ford territory and we did a second hand engine for they guy and only charged him for the second hand engine.
Or the engine shop never pressure tested the head..... They said they did though.

Teekay tester won’t pick up leak between cylinders, into crankcase or externally.

You won’t reliably and consistently pick up small leaks with a compression test though. If it’s a massive leak, it’s a different story.

 

[gtrboyy]

Backyard mechanics works well enough with common sense & specs for engine

oil pressure test hot & cold - low oil pressure below spec got issues.

compression test - warm engine up do dry test the wet test...figures will tell where to look if out of spec.
(all cylinders within 10% means even wear)

ol' rev tune after a drive -black(fuel) blue/grey(oil) white (water) then look for cause.

pressure test coolant system(20-30mins) - visible leaks fix obvious,still looses pressure no visible leak it's internal


or pay someone for leakdown test if really concerned.

 

[shane_3800]

Teekay tester won’t pick up leak between cylinders, into crankcase or externally.

You won’t reliably and consistently pick up small leaks with a compression test though. If it’s a massive leak, it’s a different story.

Every cylinder to cylinder leak I've encountered the car has come in either not starting or running very rough. A compression test picks it straight up. That being said all the cylinder to cylinder leaks I've encountered have been on 4cyl engines. But V engines usally have a little more meat between cylinders.
I agree the leak down test will pick up small leaks which will likely be valve issues.

 

[EYY]

Backyard mechanics works well enough with common sense & specs for engine

oil pressure test hot & cold - low oil pressure below spec got issues.

compression test - warm engine up do dry test the wet test...figures will tell where to look if out of spec.
(all cylinders within 10% means even wear)

ol' rev tune after a drive -black(fuel) blue/grey(oil) white (water) then look for cause.

pressure test coolant system(20-30mins) - visible leaks fix obvious,still looses pressure no visible leak it's internal


or pay someone for leakdown test if really concerned.

I paid $41 for my leakdown test kit. Before that, I’d made my own. It’s just a fitting for the spark plug hole and a gauge, assuming you have a regulator and compressor already. I mainly purchased the kit for the extra fittings lol

Cost difference between a compression tester and leakdown test kit is negligible.

Had a wh l67 that dropped a valve seat and a v6 prado with a smashed valve shim. Didn’t take long to diagnose with the tester because I could quickly figure out which bank was causing the issue. They’re especially useful when intake reversion is causing rough running because an intake valve is damaged, for example.

 

[gtrboyy]

$41 for leakdown tester is worth it for the time saving.

They were exxy as hell back when I was in the trade & when left it also no room for a compressor or air tools.

Don't necessarily need those tools to find faults but if it's something you'll use a few times it's worth having especially that cheaply.

Want to get me one of those cool camera scopes & 3/8 milwaukee ratchet one day.....just cbf'd lol

 

[Cannman07]

I've removed the intake manifold and found this. Intake manifold gasket leak or head gasket?

 

[losh1971]

I'd say manifold gaskets, the heads are not a common place to leak on these. Plus if you had a HG leak it would have likely affected your compression.

 

[Cannman07]

I'd say manifold gaskets, the heads are not a common place to leak on these. Plus if you had a HG leak it would have likely affected your compression.

I had slightly low compression on the front, not a big difference but that could be caused by the manifold gasket leaking?