I’ve got a '94 1.8 Eunos Roadster with just over 100,000 miles.
Here’s the background info: Last summer one of the heater hoses decided to enter the next life and perished in the middle of rush hour traffic. Cue lots of swearing and a temp needle zinging to ‘H’ on the gauge quicker than a quick thing. I managed, after a minute or so, to get myself in a safe position to stop. All of my coolant had p1ssed out in that time too!
Roll on to now when I’ve finally had the chance to start working on it, I’ve replaced both heater hoses, the CAS O ring seal and the Rocker cover seal too just to make doubly sure that no hot oil is going to be ruining any pipes soon!
After talking to some of the old boys who live down my street, who are currently working on this little beauty…
…they told me that I’ve most likely warped and cracked the head due to the intense heat. So I bung out the old compression tester to see the tell tale signs of a cracked head. However, the results have turned out like this:
I’ve ignored the first test as I think I didn’t screw the compression tester on correctly. The test was done on a cold engine and I didn’t put my foot on the throttle at all (so I may have done the test wrong again).
What do you think of those results? I was told anything below 90psi, and that any significant flutuation in psi, would show that I had cracked the head. Opinions are very welcome as I am about as beginner as you can get with mechanics, my cobwebbed filled wallet has brought about this sudden desire to DIY with regards to the engine!
Hi, you should really have opened the throttle fully and also disconnected the coil to prevent stressing the HT.
The test can be helpful if, say cyls 2 and 3 (next to each other) were both low, say 70psi, and 1 and 4 were ok then you could guess the gasket had gone between those two. Looking at this though I see no cause for worry as all are pretty good. I’d get it up and running before starting to worry about what may have happened. If you were fairly quick I doubt any damage has been done
Thanks for the advice! I am a proper newbie at this stuff!
Yeah the next step is to repressurize the cooling system so that should throw up any signs of a borked head if it has warped. Fingers crossed as I want to get out and enjoy this simply fantasticly dry summer we’re having haha
Looking at the numbers and assuming the guage is accurate, all of the cylinder pressures are below what I would normally expect to see on a `94 1.8 Eunos, a healthy figure would be more like 170-185psi.
The guage I use allows for the engine to be started on the other 3 cylinders and briefly revved to give a max cylinder pressure whilst the engine is warm.
Just to add, I understand the maximum shop manual limit for a head skim is 15 thou although its ok (in my experience) to skim up to 35 thou if needed to get a true flat face if needed. Good idea to have the valve seats checked also as excessive warping can tend to loosen them.
These numbers are fairly useless, they need redoing properly to get anything useful out of them.
Given that she overheated and you didn’t manage to stop immediately (a minute or so is about 59 seconds too long) I would definitely do a compression test before getting too far from home, even just for peace of mind.
Right well I’ve figured that while work aren’t pushing for huge hours until August I have enough time to sort the Mazda properly. So, as of tonight there is a large package containing a new water pump, full head gasket set and a timing belt set all heading towards my door. For some bizarre reason i am going to try and do this myself with some tuition from one of the old boys who lives down the road. I am going to do a full port and polish on the top end aswell since it won’t do the car too much harm!
Wish me luck, i’ll post up photos of the work plus my battered and bruised hands.
How did you get on. I recently had the radiator burst on me but stopped immediately. Now I don’t have the facilities for a head rebuild or anything so involved. What kind of compression tester do I need to see if the head and gasket is ok,. and also what do I ask a garage for to run a full compression test. I think if the gasket’s gone, I might need to get someone to do a gasket change and skim,. How much could that cost,.? Does anyone know a decent place to get this done in North West area.? Hopefully I won’t need that? fingers crossed.
The engine seems to run just fine on start up so hopefully the new radiator, Radiator cap and Fan switch on the Thermostat housing (which haused the overheat) will solve the problem. Any help would be appreciated.
